Select specific resx file

A form in my app contains a button with an image , so the frmMyform.resx file contains btnMyButton.image ... that's clear ! Now, I want to add another button to the form with the same image. Ok, I can copy the button, rename it, ... But what if I just add a new button and want to select an existing (it's somewhere in my project right ?) image via the new button's Image property ? There's just Resources.resx in the project resource file combobox :confused: What's the idea behind this approach ?