"They run around."
Translation:De løper rundt omkring.
Both “de løper rundt” and “de løper omkring” are also correct. “De løper rundt” could also mean that they are running around something, such as around the house. “De løper rundt omkring” would mean that they are running around in some particular area without any particular plan or direction, though the two other sentences can also have this meaning. In most situations they are interchangeable.
Source: taral - https://www.duolingo.com/comment/8786484
'omkring' is used more like an adverb in this case, emphasizing that they don't run anywhere in particular, as opposed "De løper rundt huset", which would imply that they were running around something specific.
Om igjen is also something we say in Norway, You can omit om but I think it is not so nice without om. It has to do with the language and it's melody. It is a very good idea to listen to NRK.no. If you listen to Alltid nyheter, you get Norwegian news in Norwgian, mostly in bokmål, BBC news and Swedish news in Swedish all day, and mostly Norwegian news.
De løper rundt omkring is an expression. When I saw it here, I immediately was thinking about children running around in a garden, playing. De løper omkring is the same, but I like De løper rundt omkring better. De løper rundt is for me running around something. Like 'The dog is running around the house' .