[BUG] Some templates are duplicated during stratification

[liunelson]

1. I start with a simple compartmental model (SCRHD)

2. I use stratify to stratify the model by vaccination status u, v but only the variables S, C are stratified

   model_vax = stratify(
   model, 
   key = "vaxstatus", 
   strata = ["u", "v"], 
   cartesian_control = True, 
   structure = [],
   concepts_to_stratify = ["S", "C"],
   params_to_stratify = ["a", "vaxCtoH"]
   )
   model_vax.annotations.name = "SCRHD Vax"

3. Note that two templates (H -> R, H -> D) are duplicated and that should not happen

Relevant AMR files:

• starting model, scenario2.json
• stratified model, scenario2_vax.json