inno setup constants and parameters are duplicated

Based on the comment from Martin. Suggesting to take a look at Passing in version number to Inno Setup compiler.

Turns out I overcomplicated things. You can easily pass parameters to the compiler for pre-processor variables. In my situation MyAppVersion.

What I did in Inno Setup:

#ifndef MyAppVersion
  #define MyAppVersion "1.7.24"
#endif

And when compiling it looks like this: ISCC.exe myProg.iss /DMyAppVersion=1.7.14