The most common bolting on both English & Continental doubles uses the double underbolt. On many of these, the front lug is shaped to cam the bolt back on closing so the top lever returns to center when the gun is either fully open, closed or disassembled.
Most American doubles use a latch to hold the top lever to the right except when the gun is closed. The latch may have been lost or someone could have removed it intentionally, preferring to hold the lever over for closing than to have it be latched over when disassembling & having to push the latch to return it to center.
