It's a tange headset. The post looks like it could potentially be super record. The parts appear older than the frame, at least the brakes are I think. The RX 100 stuff is from the 90s so it has been modified to keep up with technology it would seem. It would be reasonable to assume that it was built up with a mostly dura-ace group to begin with.
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1 Super Record bike, 1 Nuovo Record bike, 1 Pista, 1 Road, 1 Cyclocross/Allrounder, 1 MTB, 1 Touring, 1 Fixed gear