discrepancy in marriage dates

I went through some films looking for the marriage dates of my husband's grandparents in Mascota, Jalisco, and came across two different dates. The first date was in April 1900 and the other in January of 1901. I don't know if they had to go to the church first and do something before marrying, or if they came back months later to sign something or what. I looked at another couple who got married the same month. The first date was at the beginning of Paril and the other was a few days later. I don't know if anyone may know why the dates don't match? Is there any way to knkow which is the correct date? Thanks!
Lavaniya Jimenez