Sentence:  A little fearfully now, Pollyanna felt her way to these bags, selected a nice fat soft one (it contained Miss Polly's sealskin coat) for a bed; and a thinner one to be <WSD>doubled up</WSD> for a pillow, and still another (which was so thin it seemed almost empty) for a covering. 
Meaning of the word marked with <WSD> tags:  To have a secondary use.