Error In Page

Error Message: Item has already been added. Key in dictionary: 'RSSLinks' Key being added: 'RSSLinks'

Stack Trace:
System.ArgumentException: Item has already been added. Key in dictionary: 'RSSLinks' Key being added: 'RSSLinks'
at System.Collections.Hashtable.Insert(Object key, Object nvalue, Boolean add)
at Dea.MasterCalendar.Configuration.MCParameters.a(String A_0)
at Dea.MasterCalendar.Configuration.MCParameters.GetRSSLinks()
at MasterCalendarMaster.showLinks()
at MasterCalendarMaster.Page_Load(Object sender, EventArgs e)
at System.Web.UI.Control.OnLoad(EventArgs e)
at Dea.Web.Core.BaseMasterPage.OnLoad(EventArgs e)
at System.Web.UI.Control.LoadRecursive()
at System.Web.UI.Control.LoadRecursive()
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

Additional Information
ErrorCaughtBy: ExpectedError.aspx
PatchNumber: 201805210
ClientName:
Product: