Warning triggered by asgi.OpenTelemetryMiddleware

Describe your environment
Python: 3.10.7
opentelemetry-instrumentation-asgi: 0.33b0
opentelemetry-api 1.12.0
Fastapi: 0.79.0

Steps to reproduce
Setup the asgi middleware with fastapi as following:

app = fastapi.FastAPI()
app.add_middleware(OpenTelemetryMiddleware)
# Configure OTEL exporter

What is the expected behavior?
We should not see any warnings.

What is the actual behavior?
The following warning is raised multiple times.

An instrument with name http.server.duration, type Histogram, unit ms and description measures the duration of the inbound HTTP request has been created already.

Additional context
Seems to be related to https://github.com/open-telemetry/opentelemetry-python/issues/2558. This is the code triggering the issue

https://github.com/open-telemetry/opentelemetry-python/blob/75313b6c6d58945c1401622b6683ccdd28657984/opentelemetry-sdk/src/opentelemetry/sdk/metrics/_internal/__init__.py#L195-L202

I imagine that somehow FastAPI is creating multiple instances of the middleware, and hence the instruments are created multiple times.

Labels: asgi, warning, fastapi

Reproduce the FastAPI setup with OpenTelemetryMiddleware and read opentelemetry-sdk/src/opentelemetry/sdk/metrics/_internal/init.py around lines 195-202, alongside issue 2558. Trace why the http.server.duration instrument is created repeatedly and identify the relevant instrumentation path. Done means the reproduction no longer emits duplicate-instrument warnings, with regression coverage if the repository provides a suitable test location.