The Entity Collision Problem (ECP) describes a representational failure mode in which multiple distinct entities are incorrectly merged into a single representational space, or a single entity is fragmented across several incompatible representations. The concept operates at the level of observable representation rather than system internals. It provides a descriptive construct for analysing failures of entity boundary integrity in AI-mediated interpretive systems. This document provides the canonical definition of the Entity Collision Problem as part of the EntityWorks Standard. Output Origin Uncertainty (OOU) is a related concept within the EntityWorks Standard describing situations in which an observer cannot determine whether an output was produced by human independent thinking, by a generative AI system, or by an unobservable combination of the two. https://doi.org/10.5281/zenodo.19001500