Duplicate shower items?

What do you guys do if you receive duplicate items at your shower but there is no receipt provided? I’d like to return a set but I imagine that’s not possible without any receipts?

Also, is there a way to exchange diaper brands? We received a ton of diapers but they’re all various brands and I was hoping to switch out one or two of them to my preferred brand. I wasn’t sure if this is a feasible option considering (again) there was no receipt provided.

None of the above was purchased off my registry and I have no idea what store they were purchased from.

Thanks!