color prints differently from separate images; confusion

[icy]

hi.

We are using Windows 10 Pro 64bit and Gimp 2.10.22.

My sister has created 2 different images.  Each has the same hexadecimal code for a shade of green; however, one image’s green prints MUCH lighter then the other image’s same shade of green.  We want both images’ green shade to print exactly the same.  (It’s supposed to, obviously, since both shades of green share the exact same hexadecimal code.)

Please enlighten us of the solution.