Mounted archer, Mounted archery.

[Nicos]

How this feat

Mounted Archery (Combat)
You are skilled at making ranged attacks while mounted.

Prerequisites: Ride 1 rank, Mounted Combat.

Benefit: The penalty you take when using a ranged weapon while mounted is halved: –2 instead of –4 if your mount is taking a double move, and –4 instead of –8 if your mount is running.

Interacts with

Mounted Archer (Ex)

At 4th level, the samurai becomes skilled at firing ranged weapons while mounted. A samurai only takes a –2 penalty on attack rolls with ranged weapons while his mount takes a double move. This penalty increases to –4 while his mount is running.

[Pharmalade]

I think the fact that it says "halved" and then outlines what halved normally means indicates that the two effects stack. I also seem to recall it being mentioned in another thread that they stack. (That is -1 for double move, -2 for running.)

[Umbranus]

I just wanted to make a thread asking the same when I remembered to first use the search function.

I would think that it works as Pharmalade said. Any other opinions on this?

[Thread Necromancer]

I concur.