Can the cables of LS C300d be shared with the 5-pin male to male connection cable of LS C120d II?

No, they cannot be shared as their cable specifications are inconsistent. The 5-pin male to male cable of LS C120d II can temporarily light up LS C300d, but it cannot be used for a long time. When used at maximum power, it cannot drive LS C300d and there is a risk of burning the cable. It is recommended to use the original specification cable.