What's the point of giving someone two life sentences?

Several reasons.

First, "life" doesn't necessarily mean until they die. For example, in California, a punishment that's listed as "life" means they're eligible for parole in 7 years. Only if the sentence is "life without the possibility of parole" will it actually mean they spend the rest of their life in prison.

Second, a separate sentence for each crime can give some closure to each victim or victim's family. They can know that the defendant got a life sentence for the crime against their loved one and the bad guy didn't get a "free" crime.

Finally - and this one is especially true if the defendant gets two (or more) life terms in cases arising in multiple jurisdictions or in multiple cases. Suppose a "life" case was overturned in the appellate court. Without a second sentence in place for the defendant to serve, technically he could be released unless he was being held pending trial on another case. Because appeals can take a while to sort through, it could be better from the prosecution's standpoint to try and get another life sentence while the evidence is still fresh, witness' memories haven't faded, etc. Otherwise, they would have to scramble to prosecute a guy years later when they thought "why bother - he's doing life" on another case.

Silent Serenity, has a good point, but did not explain it very well. Let me try to do a better job. As Answer Guy explained, a life sentence does not necessarily that the person receiving it will spend some period of time in prison and then become eligible for parole. If the convict is granted parole then he/she will spend the rest of the their life reporting to a parole officer while living with the general public. It is only a sentence of life without parole (or death) that definitely means that the convict will die in prison.

Now how much time the convict serves before he is eligible for parole will depend on the crime of which he is convicted and the jurisdiction which convicts him. If a person is given multiple convictions and multiple life sentences, then there are two possible ways in which he could be required to serve the sentences (concurrent or consecutive). If the sentences are set to run concurrently, the the convict serves these sentences all at the same time. So, he will be eligible parole once he finishes the mandatory prison sentence. If, on the other hand, the sentences are consecutive then the convict must complete one sentence before the next one goes into effect.

As an example, let us say that you are convicted of three murders, each of which carries a sentence of 20 year to life. If sentences are concurrent, then you serve all three sentences at once and will be eligible for parole in 20 years. However, if the sentences are set to be consecutive, then you must serve the sentences one after the other. So you would serve 20 years in prison on the first conviction and then be eligible for parole on that conviction. However, at that point the sentence on the second conviction would kick in and you would have to server another 20 years before you would be eligible for parole on it. Once you completed the second mandatory 20-year term, the third sentence would go into effect meaning that you would have to server yet another 20 year before you would have completed all of the minimum prison time and actually become eligible for parole. So, my making the three sentences run concurrently, the judge in effect turns the three 20 to life sentences into a single 60 years to life sentence.

Now, I have explained this is terms of multiple death sentence because that is the context of the question. However, these principles apply whenever multiple sentences are handed down against a convict.

Two consecutive life terms are imposed by a judge when there
are two crimes committed by the defendant.Both life sentences
are usually handed down as a result of murder.

The purpose of giving two life terms back to back rather than
concurrent ( served at same time ) is to lessen the chances
of parole. A life term can mean 25 years before a parole hearing
so to begin the second life sentence means another 25 years
before the convicted can have a parole hearing.

In some places a sentence of 15 years to life means
an early parole hearing. It varies in different countries and jurisdictions.

In Canada the non-parole period is 25 years for 1st degree murder,
and for 2nd degree murder, the non-parole period ranges
between 10 and 25 years. If a non-parole period is more than
15 years, the prisoner can apply to the National Parole Board
for parole consideration after 15 years. Other crimes, including
robbery, rape and burglary, have a maximum sentence of life.
In these cases, the non-parole period is seven years.

In Europe it there are different laws and interpretations
of a life sentence.

In actuality when given two or more life sentences
there is little chance of parole.

the criminal might be a Buddhist

Assuming that the two sentences are for different crimes, e.g., two murders, the two sentences in effect reflect the gravity of each crime. The function of the penal system is complex and one of its purposes is to provide a sense of closure to the victims and/or their families left behind. If someone murdered more than one person, it would not be fair to each family if the perpetrator did not receive the maximum penalty under the law for the crime committed against their own family member. It would be like a '2 for 1' deal and that doesn't equal justice in many people's estimation.

Why not give a life sentence without possibility of parol instead of complicating it and giving crazy numbers like 19 life sentences as in the case of Chester Stiles!!!

In case one of the convictions is overturned or reduced.

No point whatsoever............a life sentence is exactly that....it is never completed until death. Subject to remorse and good behaviour the defendant may be given parole but he still has the possibility of having parole revoked if he as much as steps out of line once. In that case he would be returned to prison to complete his full sentence behind bars.
No-one gets sent to prison FOR punishment.........the loss of liberty IS the punishment.

Because each individual crime needs to be seen to be addressed individually , especially for the families of the victims .

In case of reincarnation.

Because some people are so sick they'll keep your corpse in that thar cell till the zombie apocalypse, and then re-kill your ass.

a)france and belguim are now the foremost glass making countries of the world.
b)the basis of ordinary glass is silica.
c)glass manufacture is an ancient art.
d)silica is generally in the form of clean,pure sand.
e)the egyptians and the Greeks manufactured the glass with technical perfection.

To let the defendant know that you are really pissed off.

When a felony is committed, and it involves the homocide of one or more persons, a jury may give this sentence, instead of a death sentence. the facts of the case, will have a great bearing on the juries decision. in order to keep a convicted homocide felon in prison, the facts of the case may warrant more time than one life sentence will allow. sentenced to one life in prison, only means about 10-20 years to actually serve, depending on the state involved. if the jury believes this is not enough time to serve, they can impose and additional life sentence, again if the facts of the case warrants it. thus, two life sentences would be a total of 20-40 years to serve. i believe the theory is that because at the end of the time served, maybe the felon would be too old to commit any other crimes. juries are charged, by the court, to render an honest, unanimous verdict in each heard case. juries just about have limitless powers when it comes to a verdict, except in specialized cases.