Very difficult to identify at that young age.
Are you claiming that you purchased these as terrestrial orchids?
It could be weed seeds germinating before the orchid seed does but you just can't grow orchids from seed easily!! There is a very important relationship that exists between the seed and a microrhyzal fungi. This symbiotic relationship exists between all orchids, not just terrestrial ones.
Without the fungus, the orchids can't possibly servive.