Single vs double hook trigger?

[Comanswoodwork]

Is there any advantage that one has over the other? If not why produce 2 different kinds? I ask because I recently purchased a new Zastava PAP and it is cutout for a double hook trigger but only has a single hook tapco installed.

[tbonnin]

With a single hook could it be that there is an uneven pressure on the trigger pin that could cause more felt drag? Best I could think of.

[frotentoaster]

I have had rifles with both the single and double hook triggers, and I can honestly say that I could not tell the difference. That being said, you'd think the double hook should be smoother...

[old Grump]

Is there any advantage that one has over the other? If not why produce 2 different kinds? I ask because I recently purchased a new Zastava PAP and it is cutout for a double hook trigger but only has a single hook tapco installed.

The way I read it is the double hook is strictly semi-auto, single hook can be used either way.