I put Grout Boost in when I did the grout on my kitchen counter-top. Is it OK to put another sealer on top even though I used the Grout Boost in the grout?
Well... since you used it...
If another sealer will penetrate, then it didn't work in the first place.
If it does not penetrate, then its working...
It hasn't gotten stellar reviews for performance.
I did find a thread that suggests resealing with solvent based sealers rather than water based sealers.