Python, 85 bytes

This is pretty brute force, I'll look into regex solutions next.

lambda a,b:a.lower()in['2','to','too','two','t0']and b.lower()in['b','be','bee','b3'] 

Python, 85 83 bytes

@Manatwork saved me two bytes.

This is pretty brute force, I'll look into regex solutions next.

lambda a,b:a.lower()in'2 to too two t0'.split()and b.lower()in['b','be','bee','b3']