These stamps were used in the states under French mandate after WWI (among them Lebanon)
around 1925.
The text is 'DOUANE DES ÉTATS SOUS MANDAT FRANÇAIS'
(Customs of the states under French mandate).
I do not know why there were a blue and a green stamp.
(blue stamp scanned by Christian de Ryck, green stamp scanned by Pascal Pette>)
This is a stamp in use c. 1950.
The text is 'DOUANES LIBANAISES' ('Lebanese customs', these cards were
imported) below a cedar tree, and an
Arabic inscription above it.
This is a stamp probably in use c. 1960.
It is similar to the previous one, but the text this time is
'DOUANES DU LIBAN', and the cedar tree is wider.
This stamp was also on imported cards.