Wiktionary
vb. (context transitive English) To find and put together in the same place.
Usage examples of "collect up".
In theory they're limited to one part in ten, except they can collect up to nine parts in ten of any tar being imported.
I had a scarf ready to take the pressure of the cord, I did it real tight but not so as to hurt, then I was going to gag her, but first she had me collect up the wash-things she needed and (I was very glad to see) she had chosen some of the clothes I had bought.
I want the reserves spread out along the edge of the woods so they can collect up men who run away and get them organized.
You collect up your former ship's company, unless you want to leave the garrison on the Diamond, in which case Captain Edwards will let you have an equivalent number of men from this ship.