CAN I HAVE 2 SETS OF HOMEPODS ON ONE APPLE TV

if you have an Apple TV 4k you can set one pair of the big HomePods (not minis) to home theatre: Set up home theater audio with HomePod and Apple TV 4K - Apple Support (CA). I believe you can only choose one or one pair to be the default audio, but there’s an option to add more in this setting that will display in the AirPlay menu.

Either way you can still use as many as you like with AirPlay with or without this setting.

Well it won’t be true surround sound but you can put them in the rear and get all 4 to play in sync