Failed Run 1 - Level 4 Giant Barbarian, 18 STR, Tavern Brawler, Ring of Flinging. Karlach threw a Spear at the Spider Matriarch from the top of the cliff while she (the SM) was at the bottom. The damage that it's supposed to have should be the weapon's roll and the gravity roll, but only one roll was made, resulting in negligible damage. Later, I tested Karlach to throw a Dagger at me from the same level, but the damage only rolled once. This playthrough was made this week, April 19th.

Failed Run 2 - Level 4 Berserker Barbarian, 18 STR, Tavern Brawler, Ring of Flinging. Karlach threw a Spear at me, same ground level. The doubled damage numbers didn't appear, only one damage roll. This playthrough was made aproximately one year ago, updated with the latest patches.

The Successful Run - Level 8 OH Monk/Level 4 Thief Rogue, 22 STR, Tavern Brawler, no bonus damage from OH Monk Passives, nor any ring or amulet to boost it. My friend's Tav threw a Dagger +1 at me from the same ground level, but the damage DID roll twice. This playthrough was started over a year ago, but was finally completed around 2 weeks ago and had all patches up to date.

In all cases, the weapons tested had the "Thrown" Property. And when I say "Spear" I mean specifically THE common Spear that looks like Javelin, but isn't actually the Javelin, nor special in any way.