The normal AN2 is definitly and per AOM a multi crew aircraft.
AFAIK only a special variant is rated for single pilot ops, and I would not encourage this. The engine is pretty work intensive and you'll be happy to have 2 pilots or at least an FE (which also makes it multi crew, but only one driver) available to work the multiple engine controls while the other pilots the aircraft.
When I did the type transition in Bulgaria, I did a direct entry to PIC, as I had the necessary license (CPL) and after an evaluation flight with the head of the FTO (wasn't called that way then, but whatever) who pronounced my skills sufficient to go directly left. Nevertheless, I have flown several missions after this from the right hand seat as FO and logged the hours accordingly. The Bulgarians were very clear on that fact and the operator asked to see the logbook after every periode of training/flying to sign it off.
The only single pilot variant I have seen in Bulgaria was a "M" type agricultural one which was cleared for single pilot ops if the pilot was as well, otherwise it was flown like the others in 2 man configuration.
I have not flown in BG since EASA invaded, all my former babies are now stored in Dobrich awaiting their fate and are for sale... The para plane at a local field here is flown in a 2 man config and under Bulgarian Civil register, so I reckon the same rules still apply.
Therefore I should think that you should be able to log those hours, unless the operator of your aircraft and/or the registrar state clearly sais it is a single pilot aircraft. For JAA/EASA Purposes that rises the ugly question if a multi crew endorsement is needed for this, but then again, as it is an annex II plane, the question would then be if this applies or if the type rating as multi crew is enough.
Best regards
AN2 driver.