i had a double buggy many years ago.
it was ideal for a 2 year old and a 6 month old.
it was a maclaren. back in the late 70's they had stripey canvas, if anyone remembers them. a basic one which when folded wasnt very big and left plenty of room in the car boot .
i used to have problems getting into some shops as the doorways werent wide enough.
debenhams used to be a pain as i used to get electric shocks in the handles from the static going over their flooring.
you need extra long arms too unless you use the handles from one of the buggies.
as for todays models, i wouldnt know, but they seem to have every attachment possible which adds up to a weighty larger machine!!!!
good luck with your search.
h.x