Why it happens
- The two characters look too alike: same gender, similar age, same-coloured clothes.
- The prompt doesn't say who is on the left and who is on the right, so the subject of each action is vague.
- The shot has crossing movement, a hug or occlusion, and the model merges their features.
How to fix it
Separate the two characters by colour, hairstyle and silhouette, e.g. one dark and one light outfit, long hair versus short.
State positions in both keyframe and video prompts: who is on the left, who is on the right.
Turn dialogue into shot/reverse shot: single close-ups plus one two-shot to establish the relationship.
In a two-shot, give only one person a noticeable action; the other just reacts slightly.
Remove crossing moves and occlusion, and keep space between them.
Before and after
Fails
Two girls argue in a hallway, shoving each other.
Works
Frame left: Lin Xia, short hair, black blazer. Frame right: Zhou Yao, long curly hair, cream sweater. They stand one step apart; only Zhou Yao leans in and points at Lin Xia, who stays still.
Prevent it next time：Design characters to look clearly different, and split into single shots at the storyboard stage whenever you can.
Worked examples
Shoot two-person dialogue as shot/reverse shot
When two people talk in one frame, identities blur, both mouths move and lip sync fails.
→Crowd scenes: a clear lead, a crowd that stays put
In crowd scenes the lead's face drifts, extras move chaotically, and duplicate or extra faces pop up.
→Flashbacks the audience recognises instantly
Flashback shots look the same as present-day shots, so viewers lose the timeline.
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