The facehugger 'tablets' had been mass produced to take to lab #2, in order to extract the black substance from the facehuggers.
Hence there are some 'lying around' outside (?) of lab #2, and there's a glass tank in lab #2.
As there are two (?) facehuggers in lab #2 in the glass tank with pipes attached to them in order to extract the black substance, presumably the staff were being (in relative terms...) safe in making the extractions iteratively rather than en masse.
This is why there are two labs, and with different dates attached: the second emerged from the discovery of the black substance.