[API] ga:pagepath has wrong values? (using custom metrics&dimensions)

Hi, I'm new here, freshly registered

For the last week I was experimenting in my shop with custom metrics and dimensions. For example I wanted to track how many times a "registered user" visits which "category" or "product". I know it should be done with "Enhanced Ecommerce" plugin, that is why I call it experiment

1. On a category page I set "dimension1" with value of user id and "metric1" with category_id.
2. On the product page I set all of the above (user_id and the category_id product belongs to) and I add another "metric2" with product_id

Api is called with parameters:

• metrics: ga: pageviews,ga:metric1,ga:metric2
• dimensions: ga: pagePath, ga: dimension1, ga:date

The result is as expected, I get which user_id visited which category_id/product_id

Sometimes, result row has wrong value in pagePath. How I know?
When category_id=5 and no product_id is set, "pagePath" should be "/category/cat-food"
But some result rows with category_id=5 has the wrong pagePath: "/category/dog-food"

I am 100% sure I never set different category metric in the same category.
It looks to me that GA is grouping dimensions/metrics somehow - I do not understand.

Any ideas why API call is giving me different pagePaths for the same metric (category)?

Thank you
cheers