Can two felones get married?

Yes, they don't ask questions of that nature when you apply for a license. However, best to check with PO if under that circumstance. Depending on the location, they may be able to get married while incarcerated.

The issue is not the marriage, it is legal to get married, :but

If either is on probation, then normally contact with other felons may be restricted, so just dating, or living with them may be a violation.

If your probation does not allow contact, the PO could demand you live a part or even violate you for the contact prior to marriage.