This is a very minor bug, but why couldn't it be solved? I'm using wxDev-C++ 7.4.2.
In Dev-C++ I also discovered that text wrote in “replacement” mode couldn't be written again once undone using Redo.
And in wxDev-C++ there's still a similar bug with Ctrl+Backspace erasing: when you press Ctrl+Backspace to erase a word, then undo it, and finally decide to redo it, the word is still here.
To avoid being a victim of this bug I usually use Ctrl+Shift+Left, Backspace; but it's a bit more annoying.