Inevitably, the two big hits, "Part Of The Union" and "Lay Down" were ripe for re-release as a back-to-back, first from A&M, in March 1979, and then later, in 1981, under licence to "old hits" label, Old Gold.
A&M reissue (also promo)
Side 2 of the promo and full releases are identical.
Old Gold reissues
The Old Gold releases came in an assortment of labels/sleeves.
German "Hits Come Back" reissues
Bearing in mind that the original release had had two versions, one with "Will You Go", the other with "New World", this is yet another pairing for the German market.