If you want matched pairs, you have to go thru Bruce Meyers at DPA in CO. Bruce can get DPA to match them for you in Allerod, Denmark....but it is special order and costs extra, I believe. The other option is Len at Core Sound, he claims to match them within 1dB for his HEB sets (since he buys them in bulk).
According to Bruce, they are within a tolerance of 2dB when they leave the factory. If you buy them on ebay as I have in the past...I have seen them off as much as 6-8dB. I warn as many people as I can about this, that it is truly buyer beware on ebay regarding those things. I had a bought four over a period of a few months back in 2002 thru a guy selling alot of them on ebay (this is before the big rush for those things....got them for $90-120/piece). They came from theater productions and had been worn many times. Some of the screens were caked with makeup. None were 'matched'. One didn't even work (the guy did send another one in it's place). When the DPA service center moved from Kitchener, ONT to CO....I took advantage of the situation by calling them up on the first day they were in business. I got them to take two of the best that I had to exchange them for DPA factory matched new ones, the whole process took about three weeks. It also cost me $400. I have a document from DPA claiming they are matched, frequency plots and sensitivity and noise measurments. The 4061's serial numbers are not consequtive, but they are within 300 units from each other, the output is identical at 6mV/Pa and the noise identical at 24dB, the plots are near perfect with respect to each other (off no more than 2dB anywhere on the curve). I will take a photo and post them on here later on today. I was in fact, screwing around with them this morning trying to get everthing in order for my outing to see Niyaz in Azabu Juban tonite. I never have to do any adjustments on the SBM to get them to match. Sonically they are spot on. Anyone who has taken the time to DL anyone of my 4061 sourced torrents will tell you this.