I am a new owner of a duplex. Do I create a new lease for the current tenants that are planning on staying? the realtor involved in the sale said I use the ones that are already in place until they expire. Can someone please comment thank you

If they are still in the middle of the lease then that is the lease that stands.  Once the lease is up you can then provide your own lease.

Any existing leases are inherited by you, including all T&C's. The only time you can change a lease is when the previous one expires 

I hope it was a good one for you

Don't change the leases...first, you legally can't - and second, you want the opportunity to increase rents and shore up lease terms to happen sooner versus later so let those suckers run out.  My recommendation is to read the existing leases and enforce the terms provided.  And, cash flow day 1 is great.  Having it cash flow month-after-month-after-month is even better - and often comes with enforcing the terms of the leases.

Congrats on your new acquisition.  

@Tina Trussoni echoing everyone else- your realtor is correct. Congrats on making the purchase!!

Thanks to all. Yes the terms are fine it's just it has the previous landlords name on the documents as well as where to send him the rent, so I wasn't sure.

@Tina Trussoni  You need to give them updated info on where to send the rent and who to contact in case of an emergency or repairs.  You can send them a letter and with that, let them know the terms of the current lease are still in place.  If you want to transition to your own lease after the current lease expires, send that to them 30-60 days before their lease expires; ie at renewal.

I'm assuming your realtor also wrote that the security deposits transfer over to you at closing.