In .ini files, using the same key in multiple sections might be buggy

[eemeli]

While reviewing the current implementation, I came across a possible bug: If you have a .ini file like

[foo]
key = foo value
[bar]
key = bar value

then the two messages will probably get entangled in Pontoon. If the keys are different

[foo]
key-a = foo value
[bar]
key-b = bar value

then everything's fine.

I'm noting this here in case anyone's affected (Mozilla's own usage won't hit this bug), but this should get fixed as a part of #3538.