The problem happens if the password can be recovered with the same phone number as used for 2FA since then anyone who steals the phone/phone account can get bot

The problem happens if the password can be recovered with the same phone number as used for 2FA since then anyone who steals the phone/phone account can get both the password reset and the 2FA SMS. However, using two different numbers means a hacker has to hack two phone accounts instead of one. At least I hope that's what they have to do.