How to add feature “don't copy when pressing command” in this c program—macPaste?

Question

https://github.com/lodestone/macpaste

https://github.com/lodestone/macpaste/blob/master/macpaste.c

With this little project, I can copy a text to clipboard with just select a text, in macOS.

This stuff saved my life, but in some circumstance, it’s a bit complex

e.g.

aaa      bbbbbbb ccccccc
aaa      ddddddd ccccccc

There are two rows above, I want to copy dddddd , and replace bbbbbb in row one:

(
   result may like this:
aaa      ddddddd     ccccccc 
   aaa      ddddddd     ccccccc
)

The fast way is double click the word in row 2, and it will select dddddd(and copy with macPaste)

Then i want to double click ddddd, and press command+V to paste, but when I select ddddd,

the word is copy to clipboard,

how to add a feature in this code, when I pressing command key, macpaste will not copy selected text