Colliding Gateway IP on WAN

Is there a way I can specify which gateway to use when there are two routers with similar ip address, maybe by mac address?

Example: There are two routers both with ip 192.168.1.1. One has more bandwidth and throughput than the other. I would like to use the fastest one all the time and ignore the other . I have tried using filter rules to try drop connections to the slow router by filtering its mac address but did not get it to work. I am not in a position to change the ip address of either of the two routers.

Do you use a separate WAN interface to connect to each of the two routers or are they both connected to the same WAN interface of your 'Tik?

They are both connected to the same WAN interface.

Such configuration is against all standards and common sense, but if you know the MAC address of the router you want to use, you can create a static arp record mapping 192.168.1.1 to that MAC address . In WebFig or Winbox, go IP → ARP → Add New.

Hi
Uplink routers should be running VRRP/HSRP if single IP address 192.168.1.1 was recommended to you as default gateway. Aassume provider will care about optimal route selection and fast router will have floating IP address active.

Alternatively, you may want to configure 2 default route entries with nexthop reachability check.
Primary default route should have administrative distance 1 and use fast router IP address as nexthop. Configure “check gateway”.
Fallback default route could have administrative distance 100 using slow router IP address as nexthop.