Spotify does not allow streaming music on more then 1 device (Phone, Speaker, laptop, ... ), at the same time.
If you want two Jooki's to work at the same time, each Jooki should have its proper Spotify Account. Creating extra Spotify accounts is best done with Spotify Family. The main steps for linking 2 Jooki to Spotify Premium are:
1) Subcribe with your Spotify Premium account to a Family account
2) define and create 2 e-mail addresses for the two Spotify Accounts for each Jooki.
3) add those e-mails to the Spotify Family account
4) log in to Spotify with first new e-mail address
5) Create playlists and favorite music
6) power on Jooki for that Spotify account
7) Play Spotify music through this Jooki.
8) Open Jooki app and create / change Playlists.
9) power off Jooki and log-out from Spotify
10) Log in to Spotify with second new e-mail address
11) Create playlists and favorite music
12) power on Jooki for that Spotify account
13) Play Spotify music through this Jooki.
14) Open Jooki app and create / change Playlists.
Both the Jooki are now on there respective Spotify Accounts.