There is a 7-page thread in the Forum on a post just about the latest version 1.03.0500 firmware update. No one mentions anything there about hearing different startup noises, regardless of what platform they are using. Some of the pilots had already flown their Mavics with the new firmware and none of them noted anything different except some details about what features are included in the upgrade.
It doesn't make any sense that some people are hearing two startup tones as opposed to only one. We may have to wait until more reports about having two startup tones begin coming in to figure this one out. No one noticed any decrease in performance after the update did they?