Moss’s post led me to remember I’d read about these tumuli in a dusty journal (Som. Arch. Soc. Proc. Bath Branch) – Thomas Bush apparently excavated them in 1909 and found ‘many flints’ (chips, scrapers, etc). Curiously he found 177 in the easterly one, but only 20 in the other. He also found some bits of burnt pottery.
“The tenant told us he understood that many years ago the barrow was dug into for the purpose of getting stones, but on coming across some bones the quarrying was stopped.”
The article also noted that the ‘twin barrows’ (as he called them, though it doesn’t mention whether this was an actual name or just his description) are immediately north of the hedge which marks the boundary between Somerset and Gloucestershire, and lie in a field called Barland’s Hill. There are springs close by, also on the boundary.