I take it an appeal member could easily ask me at an appeal "Are you appealing elsewhere" ?
I've never asked that. When I sit, I am only interested in the one school, not what other arrangements you may be making or schools you may be appealing for.
The only time I do get to know that a parent is doing more than one appeal is when they've been careless in the paperwork - they've just cut and pasted their written appeal and forgotten to change the name of the school, or there's a letter supporting the appeal mentioning the other school. It does happen