Under the Big Tent

[DG97EEB]

My impression is that the similarity is probably a coincidence. 

The object in the VMS appears to be made of two distinct parts, forming a slight angle. I think this by itself excludes that it can be a bed.
The nearby "volcano" is also quite different, pointing "outside" rather than towards the bed/tent.

It remains the fact that the two objects (bed/tent and "volcano") are rather peculiar and it's bizarre to see them together in both images.

At the risk of cross posting, it need not be Vesuvius. This is Balneum Bulla, folio 5r of Biblioteca Angelica MS 1474, a thirteenth-century illustrated copy of Pietro da Eboli's De Balneis Puteolanis. Scandone, D'Amato and Giacomelli specifically interpret the upper feature as flames associated with Solfatara which is a volcanic crater in Pozzuoli.

Edit: I meant to respond to @npcompl33t