The most correct view is that he must sacrifice an animal for At-Tamattu'

Question :

During the year 1403 AH, I was staying in Ar-Riyadh. During Shawwal I went to Jeddah and from there I went to offer 'Umrah. Then I returned to Jeddah and remained there until the Hajj season during the same year. Then I went and performed Hajj, after which I returned to Ar-Riyadh after completing Hajj and Umrah. During this year one of the brothers informed me that I was considered a Muqrin combining Hajj and Umrah and that I must slaughter an animal. Is this statement correct? Please give me a ruling, and may Allâh reward you with good.

Answer:

Many of the people of knowledge say that the Mutamatti who combines Umrah with Hajj and travels between them to Jeddah or Al-Madinah or At-Ta'if, then he assumes Ihram for Hajj from Jeddah or the Miqat of Al-Madinah if he traveled to Al-Madinah, or the Miqat of At-Ta'if if he traveled to At-Ta'if, he does not have to make the sacrifice of At-Tamattu'. Others among the people of knowledge have gone with the view that he still must make a sacrifice and the description of At- Tamattu' is not removed from him by this travel. Thus, he must offer the sacrifice of At-Tamattu'. This is the most correct view due to the generality of Allâh's Statement:

"So, whoever combines Umrah with Hajj (i.e., as Hajjut- Tamattu' or Hajjul-Qiran), then he must slaughter a Hady (a sacrificial animal) such as he can afford."

This is also due to the generality of the reported Hadiths concerning this. And success is from Allâh.

Source:
Ash-Shaykh Ibn Baz
Fatawa Islamiyah, Vol. 4 Page 98