I have a class Items with properties (Id, Name, Code, Price).
Items
properties (Id, Name, Code, Price)
The List of Items is populated with duplicated items.
F
If there is something that is throwing off your Distinct query, you might want to look at MoreLinq and use the DistinctBy operator and select distinct objects by id.
var distinct = items.DistinctBy( i => i.Id );