If they have both installed, the ECP query probably won't help.
Either way, when you submit the channel for publishing, the current unpublished version replaces the current published version (once approved). You can verify that by keeping track of the generated Access Code. If users installed an unpublished version of the channel, then they'll keep that one. It
won't automatically change to the published version once approved. They'll need to explicitly add the published version to stay current.
My Channels: http://roku.permanence.com - Twitter: @TheEndlessDev
Instant Watch Browser (NetflixIWB), Aquarium Screensaver (AQUARIUM), Clever Clocks Screensaver (CLEVERCLOCKS), iTunes Podcasts (ITPC), My Channels (MYCHANNELS)