nickolasanastasiou

There is one example species I can think of and that is in the leopard gecko keeping community. Leopard geckos have three known locus-incompatible amelanism/albinism types/"strains". It is widely frowned upon to mix any single type with a type other than itself. If one wants to make a multi-gene combination morph, sometimes a breeder tries to establish reasonable confidence in the animals being worked with and that can mean test breeding to "disprove" for an undesired albino type that may or may not be known to exist in the base animal's lineage. The aim here is to produce the resultant hets (incidentally) with the hope of not getting the test-bred albino type that season so that the following season can be focused on the target albino variant once some confidence has been established that the tested-for type is likely not present in het form in that breeding animal being tested. Another goal is to maintain outcross stock for other projects. Animals intended for blank slate outcross stock may be test bred similarly with the goal of making sure the adults intended to produce future outcross-useful offspring (and the adults themselves) are not likely to be in possession of any recessive genes that could impact any other morph project.

Since BPs still get imported, BP people (to my admittedly limited knowledge) have little to no need to do things like I have mentioned, but leopard geckos are a different kettle of fish in terms of injecting fresh lineage into projects. With leopard geckos, it is pretty much Zeus and Hera or Oedipus and Jocasta for the most part in captive populations in the US, so that is why such measures may be taken.