Duplicate IP address in mtr output - LAN router being reported incorrectly

Question

When trying to debug problems with my Internet connection, I found that when I run mtr I see that the address of my local LAN router (TP-Link TL-R860) is reported incorrectly,

% mtr -c 10 --report 8.8.8.8   
Start: ...
HOST: ...                         Loss%   Snt   Last   Avg  Best  Wrst StDev
  1.|-- 192.168.1.222              0.0%    10    1.1   1.2   1.1   1.4   0.0
  2.|-- 192.168.1.222             50.0%    10    1.4   1.4   1.1   2.0   0.0
  3.|-- ...

The router's address should be 192.168.10.1 instead. My LAN network is 192.168.10.0/24, the router's local address is 192.168.10.1 and 192.168.1.0/24 is another network the router is connected to (WAN from the router's perspective).

I'm afraid that this might the cause of my problems. I reset the router to factory settings and set up the configuration again, but still the same.

What could I do to debug the issue further? In particular:

1. Is there a way how to identify the two distinct hosts for the IP addresses, to make sure 1. is the wrongly reported router? For example, to get their MAC addresses.
2. Where does the information about the IP addresses come from? What could be the causes the router's address is reported wrongly?

3. What I also find a bit strange that mtr on any address in the outer network doesn't show the router's address at all, just the target one:

   % mtr -c 10 --report 192.168.1.102
   Start: ...
   HOST: ...                         Loss%   Snt   Last   Avg  Best  Wrst StDev
     1.|-- 192.168.1.102              0.0%    10    1.6   1.5   1.1   1.8   0.0
   

4. In the cause the router is doing something wrong, is there perhaps a workaround?

Any ideas?