As you can see from this map on the Wals.info site, there are many. More explanations on the main page.
After a quick search I did, it surprised me to see some languages on this list that seemed to use the same word for one and the indefinite article, such as Dutch. I might be wrong, it seems, so you might want to look more in depth for the ones you want to study more.
Anyway, they arethere seem to be around 100. I'll list them below for ease of reference alphabetically and ordered according to the continent.
Note: I removed thesome obvious false positives or the ones that arose as not fitting but some may remain.