eyelash growth

I dyed my hair about 2 months ago (Clairol) and now I'm thinking of dying it with henna but I'm worried it'll completely damage it.

I heard that if you dye your already-dyed henna hair with a chemical hair dye that it will burn up, fall out, or something similar…so, will the same happen if I dye my chemically dyed hair with henna?

Can I dye my hair with Henna if I've already dyed it with a chemical hair dye?