How do you know its the same bird?Bird stalking maybe?
Do you by any chance use windex?
Our giant bay window always has birds hit it. Theres just a huge "pow!" and then dead bird :(.
i once let my pet love bird out of its cage when i was 7, cause everyone was telling me it needed to fly around a bit. so i gave in and listened to them... the bird got so overwhelmed it flew right into the balcony window and SPLAT ...dead :(but id think random birds flying into windows would be kinda funny.
When I first got my dove, he'd hit the windows sometimes, but now he knows they are there.