I have just taken delivery of Stoves Stirling 800DF and noticed there is only one pane of glass in the slow oven door. Had an engineer to fix clock and he said he did not know whether there should be a second pane like the main oven. All the holes are there for the brackets. There is a gap at the top of the door.
Sorry Can`t help on this occasion it`s a Liesure I have. Have checked the spec on the Stoves site but no mention of it either, so I guess to be sure you will need to give them a ring or send them a mail.