For the purpose of Tagging sheep and goats are the same.
So if you tagged 10 sheep and 5 goats this year you'd tag them 0001-15, it doesn't matter what species. The numbers are centrally generated/held by the Eid system and they issue them in sequence. If you order Eid slaughter tags that do not have a visual number they will have an (internal) Eid number, so if your number sequence suddenly jumps by 20, that is the reason why.