### What this PR does / why we need it? When the draft model also uses vllmbackend for graph compilation, the fusion pass registration occurs again, resulting in errors due to duplicate patterns. ### Does this PR introduce _any_ user-facing change? ### How was this patch tested? - vLLM version: v0.15.0 - vLLM main: https://github.com/vllm-project/vllm/commit/v0.15.0 --------- Signed-off-by: chencangtao <chencangtao@huawei.com> Co-authored-by: chencangtao <chencangtao@huawei.com>