Visitor Stitching does not impact the Predict modeling results.

Visitors vs. Visits

Predict Machine Learning models train on visitor profiles, not visits. The actual and predicted values that display in the Model Training Details Confusion Matrix refer to the number of of visitors.

Visitor Data Filtered

When preparing for training, data is filtered by visitor_id. The model only trains on this (newest) stitched visitor_id and ignores the older (pre-stitched) ID and thus is not a problem for accounts and profiles with visitor stitching enabled.