I don't have two, so it's hard to support multiple Tablos. But let's give it a try.
First off, what version are you running? Something recent (2.4.0 is the current version)?
Take a look in this folder on your PC: C:\ProgramData\TabloRipper
You should files that look like "Cache_XXX.xml" for both of your Tablos, where "XXX" is the Tablo name. Do you see them?
Each cache is written to disk when you exit TabloRipper, so if you stick to just one Tablo from start to end, the cache should be updated with the current recording list. If you switch without closing first, it's possible the current cache isn't written when switching. So please give it a try where you just access one Tablo per TabloRipper use.
Is that what's going on?