Do Multi-Signature Wallets Require Two Separate Bitcoin Wallets? Put more simply, is it possible to set up a multi-signature wallet that takes both signatures from itself?
No, two wallets are not required. It sounds like you might be confusing wallets with addresses, where one bitcoin wallet can house many bitcoin addresses and keys. 

If you want to be able to execute a 2 of 3 multisig from one wallet you can do so with bitcoin core with raw transactions. You will have to keep track of the private keys and redeemscript yourself and save them somewhere like a thumb drive for example.

Here's a video tutorial that can guide you through creating and spending with your multisig address using bitcoin core.