Complex sentence: The town of Kotlas serves as the administrative center of the municipal district, although it is municipally not a part of it and is incorporated separately as Kotlas Urban Okrug.
Split into simpler sentences: The town of Kotlas serves as the administrative center of the district, although is not administratively a part of it. Municipally, the town of Kotlas is also separate from the district and is incorporated separately as Kotlas Urban Okrug.