I need help for Mu Developers :(

Looking for Developer for MU MOBILE
VERSION 7.3
It Just few things to fix like the MALL EDITOR
specially this one :

Server Error in '/' Application.

An item with the same key has already been added.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.ArgumentException: An item with the same key has already been added.

Source Error:

Line 20:
Line 21: var data =
Line 22: @HTML.Raw(@JsonConvert.SerializeObject(Global.Xmls.Mall.Items.Select(c => c).ToDictionary(c => c.ID, c => c)));
Line 23: var good =
Line 24: @HTML.Raw(@JsonConvert.SerializeObject(Global.Xmls.Goods.Items.Where(c => (c.ExecMagic.Length > 2 && c.Categoriy > 21) || (mallitemsidarray.Contains(c.ID))).Select(c => c).ToDictionary(c => c.ID, c => c)));

Source File: c:\Mu_Server\WWW\extensionmuorigin.online\Views\Xml\MallEditor.cshtml Line: 22

Stack Trace:

anyone can help ?

Bound items cant purchase too..

PLEASE!!!