I would say it’s more than okay if the entities are gods or goddesses from the same pantheon or they all represent the same universal sphere or planet, but with other spirits from varying traditions I would just ask them if they don’t mind having a devotional altar that is shared with other spirits. Most of the ones I work with do not mind this sort of thing, like having a Cernunnos statues on one side of the altar and an Egyptian Ra statue on the other side.
The only spirits I know of that would have a big problem with this right off the bat would be the Loa spirits as from what I’ve heard they like to have their own separate altars and with each new spirit you work with, they too will demand their very own altar. I’ve never heard of this from other spirits although I’m sure there are other non-Loa spirits out there that would also become offended at the idea of having a shared altar.
When in doubt…just ask!