I don't see much likeness with the works of Aertgen van Leyden, and it of course is an Adoration of the Shepherds (or a Nativity) and not an adoration of the magi, but the important question is who the work might then be by.
RKD, I found the same composition by Mechteld toe Boecop (ca. 1520-1598), dated 1572. This is an impressively large painting (198 by 172 cm), now in the City Museum of Kampen (Netherlands). The work for sale, while somewhat smaller, still is quite large at 154 by 123 cm. It seems unlikely that two artists would have created this large a work based on the same engraving, and I haven't found an engraving or other work that could form the basis for this, so it seems as if this is an original composition, with a copy or second version.
Mechteld toe Boecop is one of the first important Dutch female painters (excluding illuminators), and her works are very rare. Her 2 daughters also painted, but even less is known about them. The RKD lists three works by her, and three works attributed to her. 4 of these 6 are in museums (all in the Netherlands), two remain in private hands.
Museum Kampen website though, which doesn't show the complete painting but a few details.
As it stands, it probably isn't an original Toe Boecop, but perhaps the work of one of her daughters or another follower? It certainly is very interesting and should probably be researched by an expert in Toe Boecop and her circle. If it is by her or one of her daughters, it would be a major find. Even if it isn't, it is the only copy of this particular work I know off.
UPDATE: a reader alerts me to the website of Jean Moust (dealer in Old Master paintings), where the work was for sale for 28,000 Euro, described as "Unidentifeid Dutch Mannerist painter, ca. 1600".