Packing problem (same key)

[2017.02.20-15.04.07:873][984]UATHelper: Packaging (Windows (64-bit)): in
System.ThrowHelper.ThrowArgumentException(ExceptionResource
resource)
[2017.02.20-15.04.07:873][984]UATHelper: Packaging (Windows (64-bit)): in
System.Collections.Generic.Dictionary2.Insert(TKey key, TValue value, Boolean add) [2017.02.20-15.04.07:873][984]UATHelper: Packaging (Windows (64-bit)): in System.Collections.Generic.Dictionary2.Add(TKey
key, TValue value)
[2017.02.20-15.04.07:873][984]UATHelper: Packaging (Windows (64-bit)): in
AutomationTool.ProjectUtils.CompileAndLoadTargetsAssembly(ProjectProperties
Properties, FileReference
TargetsDllFilename, Boolean
DoNotCompile, List1 TargetScripts) [2017.02.20-15.04.07:873][984]UATHelper: Packaging (Windows (64-bit)): in AutomationTool.ProjectUtils.DetectTargetsForProject(ProjectProperties Properties, List1 ExtraSearchPaths)
[2017.02.20-15.04.07:873][984]UATHelper: Packaging (Windows (64-bit)): in
AutomationTool.ProjectUtils.DetectProjectProperties(FileReference
RawProjectPath, List1 ClientTargetPlatforms, Boolean AssetNativizationRequested) [2017.02.20-15.04.07:874][984]UATHelper: Packaging (Windows (64-bit)): in AutomationTool.ProjectUtils.GetProjectProperties(FileReference RawProjectPath, List1
ClientTargetPlatforms, Boolean
AssetNativizationRequested)
[2017.02.20-15.04.07:874][984]UATHelper: Packaging (Windows (64-bit)): in
AutomationTool.ProjectParams.AutodetectSettings(Boolean
bReset)
[2017.02.20-15.04.07:874][984]UATHelper: Packaging (Windows (64-bit)): in
AutomationTool.ProjectParams…ctor(FileReference
RawProjectPath, CommandUtils Command,
String Device, String MapToRun, String
AdditionalServerMapParams, ParamList1 Port, String RunCommandline, String StageCommandline, String BundleName, String StageDirectoryParam, String UE4Exe, String SignPak, List1
ClientConfigsToBuild, List1 ServerConfigsToBuild, ParamList1
MapsToCook, ParamList1 DirectoriesToCook, String InternationalizationPreset, ParamList1 CulturesToCook,
ParamList1 ClientCookedTargets, ParamList1 EditorTargets, ParamList1 ServerCookedTargets, List1
ClientTargetPlatforms, Dictionary2 ClientDependentPlatformMap, List1
ServerTargetPlatforms, Dictionary2 ServerDependentPlatformMap, Nullable1
Build, Nullable1 Cook, Nullable1
Run, Nullable1 SkipServer, Nullable1
Clean, Nullable1 Compressed, Nullable1 UseDebugParamForEditorExe,
Nullable1 IterativeCooking, Nullable1 CookAll, Nullable1 CookPartialGC, Nullable1
CookMapsOnly, Nullable1 CookOnTheFly, Nullable1 CookOnTheFlyStreaming,
Nullable1 UnversionedCookedContent, Nullable1 EncryptIniFiles, Nullable1 SkipCookingEditorContent, Nullable1
NumCookersToSpawn, String
AdditionalCookerOptions, String
BasedOnReleaseVersion, String
CreateReleaseVersion, String
CreateReleaseVersionBasePath, String
BasedOnReleaseVersionBasePath,
Nullable1 GeneratePatch, String DLCName, String DiffCookedContentPath, Nullable1 DLCIncludeEngineContent,
Nullable1 NewCook, Nullable1
OldCook, Nullable1 CrashReporter, Nullable1 DedicatedServer, Nullable1 Client, Nullable1 Deploy, Nullable1 FileServer, Nullable1 Foreign,
Nullable1 ForeignCode, Nullable1
LogWindow, Nullable1 NoCleanStage, Nullable1 NoClient, Nullable1 NoDebugInfo, Nullable1 NoXGE,
Nullable1 Package, Nullable1 Pak,
Nullable1 Prereqs, String AppLocalDirectory, Nullable1
NoBootstrapExe, Nullable1 SignedPak, Nullable1 NullRHI, Nullable1 FakeClient, Nullable1 EditorTest,
Nullable1 RunAutomationTests, String RunAutomationTest, Nullable1
CrashIndex, Nullable1 SkipCook, Nullable1 SkipCookOnTheFly,
Nullable1 SkipPak, Nullable1
SkipStage, Nullable1 Stage, Nullable1 Manifests, Nullable1 CreateChunkInstall, Nullable1
Unattended, Nullable1 NumClients, Nullable1 Archive, String
ArchiveDirectoryParam, Nullable1 ArchiveMetaData, Nullable1
CreateAppBundle, ParamList1 ProgramTargets, Nullable1
Distribution, Nullable1 Prebuilt, Nullable1 RunTimeoutSeconds, String
SpecifiedArchitecture, Nullable1 IterativeDeploy, Nullable1 FastCook,
Nullable1 IgnoreCookErrors, Nullable1 RunAssetNativization,
Nullable1 CodeSign, Nullable1
TreatNonShippingBinariesAsDebugFiles,
String Provision, String Certificate,
ParamList1 InMapsToRebuildLightMaps, ParamList1 TitleID)
[2017.02.20-15.04.07:876][984]UATHelper: Packaging (Windows (64-bit)): in
BuildCookRun.SetupParams()
[2017.02.20-15.04.07:876][984]UATHelper: Packaging (Windows (64-bit)): in
BuildCookRun.ExecuteBuild()
[2017.02.20-15.04.07:876][984]UATHelper: Packaging (Windows (64-bit)): in
AutomationTool.BuildCommand.Execute()
[2017.02.20-15.04.07:876][984]UATHelper: Packaging (Windows (64-bit)): in
AutomationTool.Automation.Execute(List1 CommandsToExecute, CaselessDictionary1 Commands)
[2017.02.20-15.04.07:876][984]UATHelper: Packaging (Windows (64-bit)): in
AutomationTool.Automation.Process(String
Arguments)
[2017.02.20-15.04.07:876][984]UATHelper: Packaging (Windows (64-bit)): in
AutomationTool.Program.MainProc(Object
Param)
[2017.02.20-15.04.07:876][984]UATHelper: Packaging (Windows (64-bit)): in
AutomationTool.InternalUtils.RunSingleInstance(Func`2
Main, Object Param)
[2017.02.20-15.04.07:877][984]UATHelper: Packaging (Windows (64-bit)): in
AutomationTool.Program.Main()
[2017.02.20-15.04.07:877][984]UATHelper: Packaging (Windows (64-bit)):
Program.Main: AutomationTool exiting
with ExitCode=1 (Error_Unknown)
[2017.02.20-15.04.07:877][984]UATHelper: Packaging (Windows (64-bit)): BUILD
FAILED
[2017.02.20-15.04.07:878][985]PackagingResults:Error: Error Unknown Error

i’m trying to packing my project, but recently started to fail cause this error, but don’t understand how to fix it.
someone can help me?

Thank you,
Fabrizio