"Duplicated declaration" after integrating rbs collection

I'm just enabling "rbs collection" in a project previously integrated with rbs. After doing rbs collection install, running rbs-enabled tests breaks on parsing sig files, on a static var which I know for sure ain't repeated:

# sig smth like this:

module A
  class B
    DEFAULT_VAR = String

> bundle exec rbs test --target "A::*" rspec
/home/.bundle/ruby/3.0.0/gems/rbs-1.8.1/lib/rbs/environment.rb:135:in `cache_name': /home/sig/jwt_token_kms/configuration.rbs:19:4...19:37: Duplicated declaration: ::A::B::DEFAULT_VAR (RBS::DuplicatedDeclarationError)
        from /home/.bundle/ruby/3.0.0/gems/rbs-1.8.1/lib/rbs/environment.rb:193:in `insert_decl'
        from /home/.bundle/ruby/3.0.0/gems/rbs-1.8.1/lib/rbs/environment.rb:177:in `block in insert_decl'
        from /home/.bundle/ruby/3.0.0/gems/rbs-1.8.1/lib/rbs/ast/declarations.rb:121:in `block in each_decl'
...

Reproduce the failure with bundle exec rbs test --target "A::*" rspec, using the configuration.rbs example from the report. Start by reading rbs/environment.rb around cache_name and insert_decl, then trace declaration traversal in rbs/ast/declarations.rb. Done means the valid static variable no longer raises a duplicate declaration after rbs collection install, while genuine duplicates remain detectable.