diff --git a/lib/sequencer/unit/import/common/mapping/mixin/provide_mapped.rb b/lib/sequencer/unit/import/common/mapping/mixin/provide_mapped.rb
index 432acb059..69a5f5d31 100644
--- a/lib/sequencer/unit/import/common/mapping/mixin/provide_mapped.rb
+++ b/lib/sequencer/unit/import/common/mapping/mixin/provide_mapped.rb
@@ -14,7 +14,11 @@ class Sequencer
               private
 
               def existing_mapped
-                @existing_mapped ||= mapped || ActiveSupport::HashWithIndifferentAccess.new
+                @existing_mapped ||= begin
+                  # we need to use `state.optional` instead of just `mapped` here
+                  # to prevent naming conflicts with other Unit methods named `mapped`
+                  state.optional(:mapped) || ActiveSupport::HashWithIndifferentAccess.new
+                end
               end
 
               def provide_mapped