I believe we did start our backups for a game and we still juggle the lineup from game to game. We're made up of a number of people who have known each other for years and we created a team for all of us to play on. Some folks (like me) were in early, so made a bunch of players to fill holes while we gathered more of our friends together. Some of those 'filler' players have starting positions with the intent to phase them out to 'backups' as the 'Backups' get more experience and can start more regularly.
We thus place all sorts of people as starters or backups just to give folks playing time and experience and to keep it fun.
If we play you, and you see a different line up, no disrespect is intended from the Dungeoneers to your organisation. Its just us trying to keep everyone involved enjoying their game.
This is all of course my own take on it. I'll defer to the Owner and GM's if they decide to say the intent is actually to disrespect you.

-G