The 14:48 from Crewe yesterday is showing as a 6-car service, with 323239 & 323226. The 23:38 from Piccadilly was saying 6 car this morning, but is showing as a 3-car now.
Delving deeper.... The 1448 from Crewe was the return working of the 1227 from Liverpool, which consisted of the same two units. I strongly suspect the rear unit was locked out of use on each working, and through passengers would have been asked to swap units during the reversal at the Airport.
323226 had arrived in Lime Street P1 at 1132, working (solo) the 0917 from Crewe. 323239 joined it in P1 at 1209, having worked ECS from Allerton depot.
According to the Working Timetable, 226 would normally have gone into P2 not P1, then departed ECS to the depot at 1140, leaving 239 to work the 1227 solo. However, on 1st July this unit swap did not happen and the two units were joined instead.
The 6-car 1448 from Crewe arrived in Piccadilly P5 at 1542. It can be inferred from RTT that 226 was uncoupled and departed solo back to Crewe via the Airport at 1549. This short working replaced the 1427 from Liverpool, which was cancelled between Lime Street and Piccadilly "due to an issue with the train crew". 239 then departed solo back to Crewe via Stockport at 1601 per its booked diagram.
So it appears the unusual double formation was to mitigate the driver shortage. It positioned 226 to Piccadilly ready to take over the partially cancelled diagram.