"Can anyone please inform me if the above enlarger needs two different condensers if I intend to print both 35mm and 6X6?
The enlarger that is on offer has two different lenses, two appropriate negative carriers but only 1 condenser, so I am a little concerned."
The short answer is yes. When set up to do either 35mm or 6x6 cm, the Durst M670 (assuming the B&W version here) takes different condensers and film carrier inserts. If you have the lenses and film carriers for both formats, but only one condenser, it may be the condenser for the 6x6 format. You can use the medium format condenser for 35mm enlarging. but the brightness of the light output will be reduced. If you have two lenses, make sure that they each have a lens board, or that they use the same threaded lens board. Finding the many accessories and conversion parts for Durst enlargers smaller than 4x5 is getting pretty hard, as ebay is the primary resource.