Heading ids are not necessarily unique when using the include or display macro

When including or displaying a page using the include or display macro, identical headings on the including and included page lead to duplicate ids.

Steps to reproduce:

1. Create a page A with content = Heading =
2. Create a page B with content

   = Heading =
   {{include reference="A"/}}
   

1. Save and view the page.

Expected result:

The two headings have different ids.

Actual result:

The two headings have the same id.