Mission Editors briefing pictures problem

Been updating some missions to multi-language and would like to know if this is a feature or an issue (DCS 1.57 stable).

Is it a rule that picture files must be uniquely named between all missions in a campaign set, even though they reside in different missions and directories, I ask because if they are not it causes all sorts of wierd issues to what is displayed when you view your briefing pictures in the ME or in game for any given mission.

ie:

For a campaign with 12 missions, each mission has 2-5 different pictures for their briefings, the pictures in each of the 12 mission are named the same, both in the Default and RU directories.

It will usually display the first picture from the first mission in all subsequent mission and the rest from the proper pictures for that mission.

Default (English) directory:

Briefing00_eng.png

Briefing01_eng.png

Briefing02_eng.png

Briefing03_eng.png

Briefing04_eng.png

RU directory:

Briefing00_eng.png

Briefing01_eng.png

Briefing02_eng.png

Briefing03_eng.png

Briefing04_eng.png

If I name them uniquely for each mission changing the Mxx to each mission number and the ending from eng or rus for the russian pics, it all works fine.

ie:

Default (English) directory:

BriefingM01-00_eng.png

BriefingM01-01_eng.png

BriefingM01-02_eng.png

BriefingM01-03_eng.png

BriefingM01-04_eng.png

RU directory:

BriefingM01-00_rus.png

BriefingM01-01_rus.png

BriefingM01-02_rus.png

BriefingM01-03_rus.png

BriefingM01-04_rus.png

Regards, Ian.