Two differnet SSA-1099s for one person

Hi, hopefully someone can help me.  I'm the executor for my parents who both passed away in 2020.  I've received my dad's SSA 1099 and TWO for my mom (same tax ID and slightly different values).  My mom's don't have post-marked dates so I don't know which was sent first.  They have slightly different benefit numbers.  One is marked SSA-1099-SM and the slightly lower valued one (but not by much) is SSA-1099-SM-UD.  I can't get through to the main SSA.  My local office says the UD form is the benefit difference she received from my dad as a spouse (so she got both values) but the web says the UD stands for update.  So the local office says they think I'd report both form for my mom, but I'm not convinced.  In fact, I'm doubting it.  I also can't seem to find any definitive answer on the web.

Anyone know for sure?

Thand in advance!