LineMarkerProvider: Duplicate Icons inside the Gutter when user edits the text of it's Anchor-Element.

The following code, originally taken from http://confluence.jetbrains.com/display/IntelliJIDEA/Line+Marker+Provider (Custom Language Tutorial) and modified, generates duplicate Icons in the Gutter-Area of the Editor if
the user edits the Text behind the "hello" inside the DocComment.

import com.intellij.codeInsight.daemon.RelatedItemLineMarkerInfo;
import com.intellij.codeInsight.daemon.RelatedItemLineMarkerProvider;
import com.intellij.codeInsight.navigation.NavigationGutterIconBuilder;
import com.intellij.icons.AllIcons;
import com.intellij.psi.PsiElement;
import com.intellij.psi.javadoc.PsiDocComment;
import org.jetbrains.annotations.NotNull;

import java.util.Collection;

/**
 *
 * hello Changing this line will cause duplicate Icons in the Gutter, if the LineMarkerProvider below is running
 *
 */
public class DuplicateLineMarkerProvider extends RelatedItemLineMarkerProvider {
    
    @Override
    protected void collectNavigationMarkers(@NotNull PsiElement element, Collection<? super RelatedItemLineMarkerInfo> result) {
        if (element instanceof PsiDocComment) {
            PsiDocComment docComment = (PsiDocComment) element;
            if (docComment.getText().toLowerCase().contains("hello")) {
                NavigationGutterIconBuilder<PsiElement> builder =
                        NavigationGutterIconBuilder.create(AllIcons.General.Error).setTarget(element.getParent());
                //Using the whole PsiDocComment as Location-Anchor
                result.add(builder.createLineMarkerInfo(element));
            }
        }
    }
}

It's not the actual code i'm working with, but the smallest possible piece of code I found which duplicates the problem.
I'm guessing it has something to do with the text of the Anchor-Element (element above) being able to change, preventing it to register as duplicate or invalidate the cached Icon directly.

My actual code shows an Icon when a certain DocTag is found inside a DocComment, but I have to use the whole DocComment as Anchor,
because I want my Icon to be shown even if the DocComment is folded.

Is this a bug in IntelliJ, do I need to manually check for possible duplicates myself?

Message was edited by: Peter Schmitz Simplified example code a bit more.