Double Go is like normal go, but with each player placing two stones for each move. Captures are only made after both stones are placed.
An alternative to komi in Double Go is for the very first move to consists of placing only one stone.
Go with multiple stones placed per move gives rise to /Limbo positions.
Note that captures occur at the end of each turn, so it is not possible to flip a (single stone) ko and fill the space in the same move.
(single stone) kos are resolved by using one stone to flip the ko and one stone to play a ko threat. /Limbo positions will end a ko, as both stones must be played to save a limbo group.
Seki positions can occur between two groups with unequal numbers of eyes below 3