Little confusing, there is a Dt125, 1G0 but it sort of blended into the MX so both kind of exist. Records back then were sketchy and model dates got a bit blurred.
The Haynes manual ISBN 1 85010 300 3 (not sure if its still in print) actually gives specs for 1G0 as a twinshock and as a monoshock if you read the specs carefully. For the UK at least.
The difference seems to be noted as Dt125 (1G0) is the Twinshock and the Dt125E (1G0) is the MX. That is not constant but common. Your engine/chassis number being 1G0-000101 onwards.. The 125E will start 2A8 that would be the Monoshock.