Environment: Windows 10, Java 1.8.0_241, PlantUML version 1.2020.22 (also reproduced it with V1.2021.0)
Initially met it in VS Code + PlanUML extension, also reproduced it in command line (java -jar plantuml.jar)
Steps to reproduce:
- Create sequence diagram
- Export diagram to PNG
- Use 'Extract PlantUML Diagram Source from Image' on file from step 2.
Diagram can be extracted and result matches initial diagram
Initial diagram can be extracted, but data is duplicated (extracted/displayed twice)