Map editor creates duplicate entries in sysmaps_link_triggers table

We have a map. It has some hosts with links. Some links are bound to 4 or more triggers.
Now i'm adding a new trigger to a link and when trying to save the map, i get an error (screenshot attached) about an
unique index violation in MySQL table.

I close the map, open it (unsaved), add the same trigger again, press Apply, Save Map and voila, it's successfully saved.
Then i'm taking next link and having same issue or not

Sometimes it helps to do all changes again, sometime it doesn't, i can't seem to figure out the cause.

The DB was upgraded from 1.8 version, maybe it's related somehow.