The Tiki Quest Tech Part rewards will not stack with existing tech parts in your inventory....even when they are dragged over the other parts.
Also, the listed rewards in your com do not match what is actually given.
It states 2 unidentified Tech, 1 unidentified E Tech, then another 3 unidentified Tech.
It actually gives 1 unidentified L Tech, 2 unidentified Tech, and 3 unidentified E Tech
*EDIT* Learn to spell jj!