The two species became synonyms in 2020. Although some researchers did not agree with the synonymization, there is no evidence against it at the moment.
Jones, H.D., Mateos, E., Riutort, M. & Álvarez-Presas, M. (2020) The identity of the invasive yellow-striped terrestrial planarian found recently in Europe: Caenoplana variegata (Fletcher & Hamilton, 1888) or Caenoplana bicolor (Graff, 1899)? Zootaxa 4731, 193–222. https://doi.org/10.11646/zootaxa.4731.2.2
(Link)
Unintended disagreements occur when a parent (B) is
thinned by swapping a child (E) to another part of the
taxonomic tree, resulting in existing IDs of the parent being interpreted
as disagreements with existing IDs of the swapped child.
Identification
ID 2 of taxon E will be an unintended disagreement with ID 1 of taxon B after the taxon swap
If thinning a parent results in more than 10 unintended disagreements, you
should split the parent after swapping the child to replace existing IDs
of the parent (B) with IDs that don't disagree.
