Multiple specifications with the same name are grouped into the same "facet" by the Intelligent Search, which can be a problem if they have different settings.

Some attributes that may be affected are the filter, hidden and indexed/searchable toggles, field type, and value position. There's no difference between being a product or SKU specification.

It is not possible to know which property will take precedence on top of the other.

For a store with:

• specification named "foo" (ID 1) set as a filter (to appear in the storefront) and with the value "bar" for a product;
• another specification named "foo" (but ID 2), which is not a filter, and with value "baz" for the same or another product.

The storefront may render a search filter for the facet/specification "foo" with both values "bar" and "baz" or even hide the whole filter.

Although the Catalog module does not block repeated specification names, this usage should be considered wrong.