Can a person perform 'Umrah during the months of Hajj even if he will not perform Hajj?

A person can perform Umrah throughout the year, including the months of Hajj and others. However, it is disliked to perform Umrah during the days of Mina for someone who is performing Hajj. If the person performing Umrah combines Umrah and Hajj in one journey, he is considered a Mutamatti'.