The duplicate characters flag (dc) enables characters to show up in the seed in more than one slot. Because certain characters are required for some questlines and every Jets of Time seed may be 100% completed, this is handled in the following way: each character is shuffled at the beginning of a seed as normal, and these characters retain their name. The name of the character controls their ability to unlock questlines; the character with the default name of “Frog” will be the character who needs to come to the Magic Cave to open up Magus's Castle, for example.

When the flag is enabled, other characters may be shuffled into these slots at random. So while there will only be one character named “Frog” (for example), and that character will keep that name, any of the other 6 could come into the slot. They will have their own sprite, but with Frog's color palette. The sprite determines which character has joined your party, which techs they can learn, and which items they may equip.

The flag can be applied using default random settings, or a player may further control manually which characters are in the seed and how many of them appear.

The battle against Magus is always randomized in Jets. When the Duplicate Characters flag is enabled, the enemy Magus will appear as one of the characters who have already been shuffled. It's important to note that here, Magus will NOT cast his ultimate tech based on the character whose sprite he shares - he will cast it based on the character whose palette he shares. So, for example, if your Magus looks like Crono, but he has Lucca's palette (orange clothes, pink hair), his ultimate tech will be Flare, not Luminaire.