entering purchase info for rental duplex with 2 separate addresses, not owner occupied

I bought a duplex in May2020. I did not live in it. 1 side came with renters that stayed and I rented out the empty side July 1st. How do I enter the purchase information as each side has its own address.  I am getting conflicting advice to enter them as separate properties and split the purchase numbers.  I repaired alot of issues on both sides and installed central air units on each.  I did not plan to, but i ended up moving into one of the units January 2021 so I want to make sure i do this right so I don't mess myself up for 2021 tax year.