Copy (?) after Melchior de la Mars, or an original?

At Horta in Brussels, they sell on 11 May 2015 a "Flemish School, 17th century" depiction of Mary Magdalen, estimated at 3,500 by 5,000 Euro.

It is a copy(?) of the Mary Magdalen by Melchior de la Mars in the Royal Museums of Fine Arts of Belgium in Brussels. It has the exact same dimensions (113 by 86 vs. 111,6 by 86,5), and seems to be painted very well. The different colour is probably a condition issue (the one for sale should be cleaned, while the one in the Museum seems overcleaned).

I can't find good price indications of what an original De la Mars would be worth, they are very rare, but it should be a lot more than the estimate. If it is a copy, it is a good one (the Galerie Moderne site gives very large images, letting you zoom in on every detail: e.g. the right wing of the angel is beautiful) and should be worth at least the top end of the estimate, but an original could well be worth ten times as much.