Duplicate prodution names

there is this problem that i don’t understand where does it derive . . .
these two ligatures are different as you can see ,
both of them in the first letter has same letter but in second part one of them has final and another one is the normal one ( isolate ) , why it keeps giving me this error , and i saw other topics saying it is duplicate glyph and you have to remove one of them but why it thinks these are the same ?
these are the codes :
sub alef-ar.fina keheh-ar.init by alef-ar.fina_keheh-ar.init.rlig;
sub alef-ar.fina keheh-ar by alef-ar.fina_keheh-ar.rlig;
also funny thing is that the same thing does not happens with other ligatures !
for example :
sub alef-ar keheh-ar.init by alef-ar_keheh-ar.init.rlig;
sub alef-ar keheh-ar by alef-ar_keheh-ar.rlig;
with this one it doesn’t give that error which confuses me .

please , is there someone that can help me with this ? . . . ( to not delete one of them and keep both of them )

The glyph names are not optimal.
The name looks like it is a ligature between two not connecting glyph? The names should looks something like this: alef_keheh-ar.fina.rlig. The positional Suffix should be the suffix for the ligature as a whole.

I just fixed a small issue with production names. I check your names.

okay , thanks , so i’ll wait for your response while i’ll try to change things like the way you mentioned ( The positional Suffix should be the suffix for the ligature as a whole. )

i think that my problem just got solved , i tried again with these codes :
sub alef-ar.fina keheh-ar.init by alef_keheh-ar.medi.rlig;
sub alef-ar.fina keheh-ar by alef_keheh-ar.fina.rlig;

and with these names :
alef_keheh-ar.fina.rlig ( left image )
alef_keheh-ar.medi.rlig ( right image )

for now . . . thanks a lot dear mr.Seifert !