You are considered a “Sailfish customer” if you have had a Sailfish device and signed in to your Jolla account previously, and bought a Sailfish X licence previously. == SORRY, my mistake, a communication problem ==
Now, sign in to https://shop.jolla.com/ with your Jolla account credentials (top right area). Click BUY under Xperia 10 II. You should see the price 29.90 € there.
Hmm, it still shows 49.90 €.
same for me although I am a “Sailfish customer” for many years 
Sorry, my mistake: a previous licence is required to be entitled to get the discount.
A previous license of what device? I have 3 purchased previous licences in my account.
Went to shop → chose the 10 II → logged in → 29,90€ (just for you my friend! 
). Seems to be a glitch in the shop if it shows wrong prices to old customers.
Just tried again and it worked fine. I do have an older license for the XA2
Yes, it works now too.
Right, I am feeling embarrassed now.
Apologies for the great confusion. It should be clear now, after fixing a configuration issue in the shop backend and after some talking.
You are entitled to the discount if you have had a paid Sailfish X licence for any Xperia device previously, or if you have used a Jolla Phone/Tablet (and signed in to your Jolla account).
Bought with discount deducted automatically! Perfect! Thank you!
Did not show up with my account for whatever reason.
Well, Jolla can surely need my additional €20 
I can’t install the android app support on the xperia 10 II , am i the only one ?
@sanginteret:
Is it that
a) It is not visible for you in Jolla Store, or
b) The installation is failing?
If case a), have you bought the licence, signed in to your Jolla account from the phone with the same account (that bough the licence) and restarted the phone?
If case b), please explain what happens. Can you install other apps, like Exchange?
it’s case b and i can install exchange without issue
Is it OK to have the same account for two devices?
I recall someone mentioned that you should set up a second account for your new device, to avoid clashes, but maybe I wrong.
I plan to keep my existing Xperia X w/ Sailfish and get a new license for my new Xperia 10 ii. Should that be feasible with one Jolla account?
Update 2021-05-28:
Contacted Zendesk and received this response:
You can buy several licences on one Jolla account. The last bought licence will be activated on the device which is restarted (or logged in on Jolla account). The licence and the device must be “compatible”, i.e. Xperia X needs an Xperia X licence etc.
So all looking good, will be interesting to go through the flashing experience again on a second device.
same here: can’t install android app support for Xperia 10 II from within the store, although:
Installation will always fail.
Anyone having trouble with installing Android App Support to Xperia 10 II,
please file a ticket on Jolla Care at Submit a request – Jolla Service and Support.
If possible, consider collecting some logs from your device.
Enable the Developer Mode. See this article.
Launch the Terminal application.
On Terminal, et super-user rights (root rights):
`devel-su`
In Jolla Store, try to install Android App Support
On Terminal, again, collect the journal log to a file:
`journalctl -ab --no-pager --no-tail > journal.log`
Attach journal.log to your ticket, please.
i have installed the android support via the terminal.
I use the following command: devel-su zypper install aliendavkin
The i forced the installation because there has a conflict between two package (apkd and apkd8)
It’s now working.
would do, but not possible yet, due to the Xperia 10 II not yet included in the drop down field for devices.
What, where? Aha, in Zendesk? A moment.
DONE.