A family of Microsoft presentation graphics products that offer tools for creating presentations and adding graphic effects like multimedia objects and special effects with text.
I don't believe so, Mark.
You can copy them to a second Master then delete them from the first; that'll send them down the bottom of the layouts gallery, a bit more out of the way, but won't make them disappear.
You could also rename the main Master slide of the second master; something dire, perhaps, like "Use these and your teeth will fall out!"
Or something a little less firm, a little more polite. ;-)