Applying for Grants.. how tacky is applying for several to fund the same thing?

[Acer]

We've had grantors allow us to move excess monies into other parts of the project after we asked nicely, but that's going to depend on the grantor. If you have a friendly contact in the grantor, you might be able to ask "Hypothetically speaking, of course" to test the waters for their likely response to changing how you spend the funds.