There has been a report of Clover incorrectly detecting TestNG test methods.
It appears to also cause the TestNG runner to run more methods which are not tests.

e.g.

@BeforeTest
public void setup() throws Exception { 
    // code in here 
}

@AfterTest
public void cleanUp() {
    // code in here 
}

may be run as tests once instrumented with Clover2.