I am furious!

Tonight I had to pay taxes to La Poste for 2 orders although I already paid them to Fasttech (Opt-in to prepaid EU taxes box ticked).
Seriously, paying taxes twice, how is that possible?

Order E103075732 : 6€ of taxes at arrival, paid to "La Poste". See Ticket Q1116WDLPD
Order B103097643 : 4€ of taxes at arrival, paid to "La Poste". See Ticket Q1116NKGJW

Conclusion, Prepaid taxes don't work for FRANCE ! Be careful !