It depends. If you received Forms 1099-R for each of you, then enter each of them. The plan administrator should have split the distribution between both Forms 1099-R to equal the total annual distribution. If this is in error, it would be best to request corrected Forms 1099-R as soon as possible.
For more information, see this article: Where do I enter my 1099-R?
Do both 1099-R's have the amount of the distribution? That does not seem right if so. Usually, I believe that a joint annuity would be on a single 1099-R with both names or if paid separately then only the amount paid to that joint owner.
Is this the first distribution? If not, then how was it handled last year?