In the name of Allah the most Beneficent and Merciful
The `Dome of Khidr` is also known as Qubbat ul Khidr. This is situated in the Haram Sharif of Al Quds and is in remembrance of Hazrat Khidr. There are many other domes in remembrance of other prophets such as Moosa Alaihis Salaam, Ibrahim Alaihis Salaam etc. These are separate to the Dome of the Rock and the Dome of Al Absa.
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Of course Allah knows best
[Answer provided by: Muhammad Salim Ghisa]