Another posthume signature

The Dordrechts Museum organized in 1962 an overview-exhibition of Zandlevens oeuvre. Catalogue number 33 mentioned: Block of houses with yellow blossoming bushes in the foreground. Canvas, 34.5 x 49.8 cm, coll. N.N. The work was not signed or dated. During the exhibition photographs were made by Denis Windt. On the picture of JAZ-1910-015, we can clearly see that it was not signed or dated.

In the year 2000 we found this painting back in an art gallery. It was signed and dated: 1912. We received a (colour) photograph, which we placed in the JAZ Museum:

JAZ-1910-015
Block of houses with yellow blossoming bushes in the foreground

Oil on canvas, 34.5 x 49.8 cm
Not signed, 1910
Owner unknown
EXHIBITED
   Dordrecht 1962 cat. nr. 33
NOTES

Since 2000 signed l.r., 1912

PROVENANCE
   Private owner
   Brabantse Kunstgalerij

What may we conclude?
1. Although there's unclarity about the provenance of the painting in 1962, there's little doubt about its authenticity. The subject, the painting-style and used technique, it is all Zandleven.
2. It seems very unlikely that the painting was signed in 1962 and that the signature was illegible due to filthiness or so. So it is very likely that someone signed the painting with J.A. Zandleven after the 1962 exhibition. Maybe to take away uncertainty re the authenticity and make the painting better sellable.