Can a quantitative hiv dna test that looks for the virus differentiate hiv 1 from hiv 2 ?

No: This is determined predominantly by antibody testing rather than by PCR for HIV RNA (This is an RNA virus). The latter test does not differentiate serotypes. Type 2 is very rare outside of Africa and seems more difficult to transmit. There are also numerous subtypes of both Types 1 & 2 and this becomes quite complex since this virus mutates continuously.