It erased the second button for me i.e. the Menu_Button_Load button after typing in Menu_Button_New like you said.
Hmmm, it seems to be erasing the original button for me - not the copied one. Like if I duplicate Menu_Button_Exit to make a duplicate called Menu_button_Exit.001. Then in the logic channel of the duplicate, I put under replace mesh, Menu_Button_New. I save the file and reload and the original Menu_Button_Exit disappears but Menu_Button_Exit.001 is intact.
Either way, that does appear to be what’s happening. I actually had something like this in Maya 4.5 where I duplicated half my model and mirrored it in the axis. Then I applied a smooth proxy to the left half of my model. It did everything fine and saved but when it loaded, the original half of my model had disappeared and I had a file error but the duplicate was ok. The way I got round it was to change the order I did things in. Instead of making a duplicate first, I made the proxy then duplicated the original. I think it was a bug there too because it seems to work ok in Maya 5.
That sort of thing wouldn’t work here, though. I thought that using the make duplicates real item in the clear/apply menu might work but it doesn’t - I think that’s meant for unlinking linked duplicates. I think it just happens with duplicates too, I tried making a new button with the same logic and it was fine. It happens with linked duplicates just the same.
So to summarize, the bug is that when you use Python to make an “edit object” actuator replace a mesh, which has been duplicated, it saves the file ok but it gives an error on loading it.
If Blender files were ascii instead of binary, it would be much easier to debug what was going wrong in the save file.