2 attached pngs (e-tickets) instead of one

-- HikaShop version -- : 3.0.1
-- HikaSerial version -- : 1.10.4
-- Joomla version -- : 3.7
-- PHP version -- : 5.6


I try to make vouchers for my vendors (hotels) available - the user can choose the design of the voucher and the value of the voucher. He gets an email with the electronic voucher as an attached png ("e-ticket"). Example: A voucher in Christmas-styling with the value of 100 Euro on it.

So I made:
- 1 serialpack for the hotel
- 1 product (the voucher to purchase)
- with the variants of the product:
1 Design Christmas, 1 Design Summer to choose
various values to choose (100 Euro,150 Euro..)

- AttachSerial - HikaSerial plugin:
2 different attachments (1 for Christmas,1 for Summer), both connected to the serialpack of the hotel

PROBLEM:
The correct serial code is on the attachment, that works fine.
But the user always gets both attachments - Christmas and Summer - in the Email.
The same serial code but on 2 pngs instead of just one.

Does this mean that I have to make a unique serialpack for every variant of my product?
Example:
1 serialpack "HotelABC-Product-Christmas" for all Christmas variants of the product
1 serialpack "HotelABC-Product-Summer" for all Summer variants of the product
and so on for every variant...
(That would mean a lot of serial packs for just 1 single product of 1 single vendor)

I thought that 1 serialpack for the vendors product PLUS different attachserials for each design (Christmas,Summer) would be enough?
What have I done wrong?

Hi Jerome,

I do agree this would be interesting: an improvement of the attach serial plugin - a development to add one new level of restriction, based on the product.

How can I achieve this? Who shall I ask? What ist the procedure?

Walter