The Walther PDP controls and shape look exactly like a Canik TP9. Is it the same handgun (essentially)? Similar to how a Glock Gen 3 and PSA Dagger relate to each other?

You’ve got it backwards. The Canik is a clone of the Walther P99. The P99 evolved into the PPQ, which evolved into the PDP.

Thanks, that's the exact info I needed! I love my TP9SF and SC, I like the PDP but really don't see a reason to pick one up seeing as what I have is so similar.

But also, why not both?

Well one is the original and the architect of the design. The other is a clone..  That doesn’t make the clone a bad pistol.
Attached File

I am a huge Walther fan and have owned most of their 9mm and several 22lr offerings. However, 3 years ago discovered Canik thru a competition shooter friend of mine, and let's just say, the Walthers sit in the safe, the PDPs were not much of an upgrade over the PPQ. Sold off one of my PDPs, kept the PDP-F for female students, but find that my Caniks (Elite Combats, Rivals, and Mete's ) outperform my Walthers, and come from the factory with all the upgrades the Walthers should have but dont and the Caniks are $100-$200 less.

💯 agree  with everything this guy mentioned ^

I have had several Caniks. I currently have a Rival Dark Side. i have added a Freedomsmith trigger and a springco reduced trigger return spring and striker plunger spring. Trigger is awesome!

I picked up a Walther PDP Pro.  It has a good trigger just not as good as the Canik Rival. I made the PDP trigger better by adding a springco reduced power trigger return spring meant for a Canik.

I like both guns. I like the grip a little better on the Walther