Duplicated modules because of query params mismatch (fixes #2255)

Editor assessment

The hmr scope earns its keep by promising dev-server relevance, and the subject describes the defect credibly: a query-parameters mismatch caused the same module to register twice, spawning duplicate instances and stale state. Grammar is slightly compressed—'duplicated modules because of query params mismatch' drops an article and a possessive—but the meaning survives, and the line stays near 60 characters even with the references attached. The issue link '(fixes #2255)' rides inline rather than in a 'Fixes #2255' footer, an established tic of this project's messages that the spec's footer section is designed to fix. No body accompanies the header, so the reproduction and the deduplication strategy are left to the PR, but for a self-contained HMR correction the message conveys enough to be useful in a changelog and a patch bump follows naturally.