Buying REO property with tenants

[Peter Deising]

Hey Everyone, looking to put a cash offer on a REO duplex that has tenants in place. according to agent, there is no record of a lease. from what I saw during my walkthrough one unit was very clean and the tenant was very friendly. the second unit worried me a little bit as there is minor damage from a dog and not nearly as clean or willing to acknowledge me during the walkthrough. Neither tenant has paid since the bank took over(around 4 months). My question is, what if tenants refuse to sign a new lease? if the tenants have a copy of an existing lease do I have to follow it out or is it null and void since the property went to the bank and tenants stopped paying?

any contingencies recommended besides inspection?

Any guidance would be greatly appreciated as this is only my second deal.