> You can try M-x debug-on-entry <RET> org-id-new <RET> to trigger
> backtrace when `org-id-new' is called and see what is calling it.
> Then, M-x cancel-debug-on-entry to disable the debugger.

Here are some news:

--8<---------------cut here---------------start------------->8---
(setq org-capture-templates
      '(
  ("mk" "Annu Grupos Ejercicios" entry (file "~/ALLES/HGs/tex/vorlesungen/HGAnnu/Hojas-Teoria/Soluciones-2024/grupos2024.org")
         "** TODO %^{Grupo} %T %^g %(org-contacts-template-name)
         :ID: %(org-id-new)
         :Link:  %a   
         :Email: %(org-contacts-template-email)
         :Grp:     %^{Gr1|Gr2|Gr3|Gr4|Gr6|Gr7|Gr8|Gr9|Gr10|Gr11|Gr12|Gr13}
         :Usuario1: %:fromname
         :Email1: %:fromaddress
         :Usuario2: %(my-extract-cc)
         :Email2:  %(my-extract-cc)
         :Usuario3: %(my-extract-cc)
         :Email3:  %(my-extract-cc)
         :Usuario4: %(my-extract-cc)
         :Email4: %(my-extract-cc)
         :Status:   [ ]
         :Hoja:     
         :Ej:       
         :END:")))
--8<---------------cut here---------------end--------------->8---

Works save the ** Problem, but the org-id-new works

Now 

--8<---------------cut here---------------start------------->8---
(setq org-capture-templates
      '(

        ("my" "Annu Grupos Ejercicios" entry (file+olp "~/ALLES/HGs/tex/vorlesungen/HGAnnu/Hojas-Teoria/Soluciones-2024/grupos2024.org" "Grupos")
         "** TODO %^{Grupo} %T %^g %(org-contacts-template-name)
         :ID: %(org-id-new)
         :Link:  %a   
         :Email: %(org-contacts-template-email)
         :Grp:     %^{Gr1|Gr2|Gr3|Gr4|Gr6|Gr7|Gr8|Gr9|Gr10|Gr11|Gr12|Gr13}
         :Usuario1: %:fromname
         :Email1: %:fromaddress
         :Usuario2: %(my-extract-cc)
         :Email2:  %(my-extract-cc)
         :Usuario3: %(my-extract-cc)
         :Email3:  %(my-extract-cc)
         :Usuario4: %(my-extract-cc)
         :Email4: %(my-extract-cc)
         :Status:   [ ]
         :Hoja:     
         :Ej:       
         :END:")))

--8<---------------cut here---------------end--------------->8---

Works concerning the ** entry but inserts the unwanted END after 
org-id-new.

I can live with solution 1 but still wonder..

Thanks

Uwe Brauer 

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