Found some strange behaviors with static DNS. Tested on 6.5 and 6.6.

Suddenly address become regexp:

ros code

[admin@MikroTik] /ip dns static> add address=127.0.0.1 name=test
[admin@MikroTik] /ip dns static> add address=127.0.0.1 name=test2
[admin@MikroTik] /ip dns static> print
Flags: D - dynamic, X - disabled, R - regexp
 #     NAME                      ADDRESS         TL
 0     test                      127.0.0.1       1d
 1     test2                     127.0.0.1       1d
[admin@MikroTik] /ip dns static> move 1 0
[admin@MikroTik] /ip dns static> print
Flags: D - dynamic, X - disabled, R - regexp
 #     NAME                      ADDRESS         TTL
 0   R test2                     127.0.0.1       1d
 1     test                      127.0.0.1       1d
[admin@MikroTik] /ip dns static>

Then I remove regexp address, it still in cache until reboot:

ros code

[admin@MikroTik] /ip dns static> /ip dns cache print
Flags: S - static
 #   NAME                       ADDRESS          TTL
 2 S test                       127.0.0.1        1d
 3 S test2                      127.0.0.1        1d
[admin@MikroTik] /ip dns static> remove 0
[admin@MikroTik] /ip dns static> print
Flags: D - dynamic, X - disabled, R - regexp
 #     NAME                      ADDRESS         TTL
 0     test                      127.0.0.1       1d
[admin@MikroTik] /ip dns static> /ip dns cache print
Flags: S - static
 #   NAME                       ADDRESS          TTL
 2 S test                       127.0.0.1        1d
 3 S test2                      127.0.0.1        1d
[admin@MikroTik] /ip dns static>

The same happened today to my RB2011UAS-2HnD with RouterOS 6.11. Had to reboot the router to get rid of the annoying record from cache.

I have the same problem - RB951 6.20