Could it be this is the emersed growth that is in the process of changing over? It looks like the emersed growth that I received when I bought this plant. It has to convert to submerged. This is one plant that has been slow to acclimate for me. 2 months doesn't sound out of the question for it to acclimate and change over.
Looks pretty much like it was grown emersed and is half switched over. The emersed form does look radically different then the submersed form. You would never guess looking at a totally emersed downoi that it had any relation to the lovely aquatic plant we know.
Yeah when I got mine they leaves were very similar in shape to yours. Since then the new leaves are longer and the side shoots look just like the downoi that we all know and love. Just give it some time. It took mine a couple of months. New side shoots should definitely look like generic downoi.