Some expressions were returning with multiple instances of the IEnumerable Visualizer when using the Debug Adapter Protocol because it did not have the logic found in the Core Visual Studio debugger to filter them out. Instead of fixing it in that layer, I decided it best to address it when constructing the evaluation result since it is never necessary to have an evaluation result with multiple copies of the same visualizer.

Added test and verified that without the proposed changes it would fail because of multiple visualizers present in the result.