The reason why your hides should be identical is that if they are not your BP will chose security over thermo-regulation.

You can make hides out of plastic bowls, plastic flower pot dish, you can purchase something like this I get mine here www.reptilesupply.com (There are different sizes available)

Remember no matter what type of hides you plan on getting they must be tight so your BP can snug in, with all the sides touching is body.