Duplicated page numbers in references - why?

My math paper is almost done, but:  Page numbers in references are 
rendered in duplicate!  I don't see what's causing this.

My doc's Lout source contains:

{
   @Reference
   @Tag {kneser50}
   @Type {Article}
   @Author {Hellmuth Kneser}
   @Title {Reel analytische Losungen der Gleichung @M{phi(phi(x))=e sup 
x} und
verwandter Funktionalgleichungen}
   @Journal {J. f. Reine Agnew. Math.}
   @Volume {187}
   @Page {56}
   @Year {1950}
}

and comes out in PS or PDF like this


[3] Hellmuth Kneser. Reel analytische Losungen der Gleichung φ(φ(x)) = e 
x und verwandter
Funktionalgleichungen. J. f. Reine Agnew. Math. 187, page 56, page 56 
(1950).

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