Again, you can not have two MAC addresses on the same physical interface, at best you may be able to get it to work somehow in niche network setups, but for any given network infra structure, it is guesswork if it works or not. See here: Changing the IP Address and MAC address during Runtime - Libraries - FreeRTOS Community Forums
Likewise, a singular MAC address but multiple IP addresses over it are a grey zone, many routers and switches may not like that at all.
@svgarcia : What happens if you leave out your Zynq target altogether, but try to cross ping your RPis in the same network setup? Does that work?