Handle Potential Duplicate Reaction Instances

[janitha-mahanthe]

Summary

Following #33 , reactions are now returned as identity-based ReactionInstance objects (List[ReactionInstance]) with no numeric indices.

This may introduce edge cases in duplicate handling.

Problem

• Duplicate reactions may be generated during detection.
• Deduplication can no longer rely on index comparison.
• Equality rules for ReactionInstance are not yet formally defined.
• May can define this in a newclass - dropping_status

[janitha-mahanthe]

Solved by #48