Assume I have LAN with address 10.0.0.0/24 with some directly attached computers and some small wifi routers. I did IP Scan from Mikrotik to LAN at address range 192.168.1.1 to 254. I was surprised to see, several matches ( around 10 ) of 192.168.1.1 and some MAC addresses. I mean something like that:
192.168.1.1 AA:BB:CC:00:01
192.168.1.1 AB:C3:09:11:A0
192.168.1.1 OB:B2:34:03:0B
and so on.

Quick thinking led me to only possible solution , that these are internal ( or say: at home ) addresses of user's routers coupled with their MACs. The default IP of LAN address of commonly used wifi routers are usually 192.168.1.1.
Indeed i.e. my address 10.0.0.5 is seen as AA:BB:CC:00:01 on ARP list and I know , that there is a router.
So my question is: how is it possible, that Mikrotik during IP scan "sees" and couples with MAC internal addresses used by client routers ? They should be masquaraded by the respective home routers.