On Windows it depends.
Is it a self drawn caret, or is it the system caret?
An indicator may be, if you change the blink rate in the system setting, will the caret be affected (even if you do, while the app is already running)
If the app draws it's own caret.... Well, I don't know.
Normally on windows, a memo component calls SetCaret or ShowCaret, from the win api. (search the code)
And then windows draws the caret and makes it blink.
This normally works well. But windows only supports ONE caret per application (across all windows of the app). So if there is a 2nd memo, that wants the caret, then the first one will loose it.