Thanks
A few questions, assuming you're not using the no-substrate method of incubation:
What substrate are you using?
Did you bake it prior to hydrating it to remove any water already in the substrate?
What ratio of water to substrate did you use?
How did you measure the water/substrate to ensure you got the ratio you were aiming for?
In our first clutches (python eggs), we had problems with fungus/mould due to excessive moisture, even when we used the commonly suggested 1:1 ratio. The next season we used a mixture of perlite & vermiculite (3 parts) and water (2 parts). We then added a layer of completely dry perlite, and sat the eggs on that. Using this method we had no mould problems. I'm not suggesting any such ratio for beardie eggs though, as I've not bred them before and I've done no research into the incubation of their eggs ;-)
Having said all of this, if it is mould, I would strongly advise you to mix up a new, drier batch of your substrate, placing it into new tubs, and then move the unaffected eggs into it, being careful not to rotate them (mark them with a pencil before moving them).
It's always better to err on the side of a drier substrate, in my (limited) experience, as you can always add more water, but it's a lot more difficult to fix it when there's too much and the eggs have gone mouldy.