Tpe used to split at York with one unit continuing to Scarborough and other to Newcastle on some services . Not sure if this still happens with the new timetable
I've not seen that, but it does remind me of this service:
1A56 2157 Middlesbrough to Manchester Piccadilly, calling at Thornaby, Yarm, Northallerton, Thirsk, York and Leeds, where the train couples to:
1K40 2224 Hull to Manchester Piccadilly, which has already called at Brough and Selby.
The 6 car 1K40 then goes forward to call at: Cottingley, Morley, Batley, Dewsbury, Ravensthorpe, Mirfield, Deighton, Huddersfield and Manchester Piccadilly