Same url cannot be set for different cultures

[andrjfrks]

Hi,
I needed to set same url for two different cultures:
/sk/zakaznicka-podpora-bulharsko -> /sk/sluzby/zakaznicka-podpora/bulharsko
/cz/zakaznicka-podpora-bulharsko -> /cz/sluzby/zakaznicka-podpora/bulharsko

However, validation did not succeeded and I'm getting an error:

There is already a existing redirect with this url.

I think this is a valid redirect.
When I copied row of first entry in db and change culture, it is working correctly.

Umbraco: 8.13.0
RedirectsViewer: 2.3.0