diff --git a/ClosedXML/Excel/XLWorkbook_Save.NestedTypes.cs b/ClosedXML/Excel/XLWorkbook_Save.NestedTypes.cs
index 0f1c4ca..356424c 100644
--- a/ClosedXML/Excel/XLWorkbook_Save.NestedTypes.cs
+++ b/ClosedXML/Excel/XLWorkbook_Save.NestedTypes.cs
@@ -99,7 +99,7 @@
                 {
                     _relIds.Add(relType, new List<String>());
                 }
-                _relIds[relType].AddRange(values);
+                _relIds[relType].AddRange(values.Where(v => !_relIds[relType].Contains(v)));
             }
             public void Reset(RelType relType)
             {
@@ -147,9 +147,5 @@
             public IXLStyle Style;
         }
         #endregion
-
-        
-        
-       
     }
-}
\ No newline at end of file
+}
diff --git a/ClosedXML/Excel/XLWorkbook_Save.cs b/ClosedXML/Excel/XLWorkbook_Save.cs
index 8dd7f14..1a4f3bc 100644
--- a/ClosedXML/Excel/XLWorkbook_Save.cs
+++ b/ClosedXML/Excel/XLWorkbook_Save.cs
@@ -578,24 +578,36 @@
                 sheet.Name = wks.Name;
             }
 
-            foreach (var xlSheet in
-                WorksheetsInternal.Cast<XLWorksheet>().Where(s => s.SheetId == 0).OrderBy(w => w.Position))
+            foreach (var xlSheet in WorksheetsInternal.Cast<XLWorksheet>().OrderBy(w => w.Position))
             {
-                var rId = context.RelIdGenerator.GetNext(RelType.Workbook);
-
-                while (WorksheetsInternal.Cast<XLWorksheet>().Any(w => w.SheetId == Int32.Parse(rId.Substring(3))))
+                string rId;
+                if (xlSheet.SheetId == 0)
+                {
                     rId = context.RelIdGenerator.GetNext(RelType.Workbook);
 
-                xlSheet.SheetId = Int32.Parse(rId.Substring(3));
-                xlSheet.RelId = rId;
-                var newSheet = new Sheet
-                {
-                    Name = xlSheet.Name,
-                    Id = rId,
-                    SheetId = (UInt32)xlSheet.SheetId
-                };
+                    while (WorksheetsInternal.Cast<XLWorksheet>().Any(w => w.SheetId == Int32.Parse(rId.Substring(3))))
+                        rId = context.RelIdGenerator.GetNext(RelType.Workbook);
 
-                workbook.Sheets.AppendChild(newSheet);
+                    xlSheet.SheetId = Int32.Parse(rId.Substring(3));
+                    xlSheet.RelId = rId;
+                }
+                else
+                {
+                    rId = String.Format("rId{0}", xlSheet.SheetId);
+                    context.RelIdGenerator.AddValues(new List<string> { rId }, RelType.Workbook);
+                }
+
+                if (!workbook.Sheets.Cast<Sheet>().Any(s => s.Id == rId))
+                {
+                    var newSheet = new Sheet
+                    {
+                        Name = xlSheet.Name,
+                        Id = rId,
+                        SheetId = (UInt32)xlSheet.SheetId
+                    };
+
+                    workbook.Sheets.AppendChild(newSheet);
+                }
             }
 
             var sheetElements = from sheet in workbook.Sheets.Elements<Sheet>()
diff --git a/ClosedXML_Tests/ClosedXML_Tests.csproj b/ClosedXML_Tests/ClosedXML_Tests.csproj
index f1c0f09..802f873 100644
--- a/ClosedXML_Tests/ClosedXML_Tests.csproj
+++ b/ClosedXML_Tests/ClosedXML_Tests.csproj
@@ -78,6 +78,7 @@
     <Compile Include="Excel\Loading\LoadingTests.cs" />
     <Compile Include="Excel\PageSetup\HeaderFooterTests.cs" />
     <Compile Include="Excel\Ranges\UsedAndUnusedCellsTests.cs" />
+    <Compile Include="Excel\Saving\SavingTests.cs" />
     <Compile Include="XLHelperTests.cs" />
     <Compile Include="Excel\AutoFilters\AutoFilterTests.cs" />
     <Compile Include="Excel\CalcEngine\DateAndTimeTests.cs" />
@@ -265,4 +266,4 @@
   <Target Name="AfterBuild">
   </Target>
   -->
-</Project>
+</Project>
\ No newline at end of file
diff --git a/ClosedXML_Tests/Excel/Saving/SavingTests.cs b/ClosedXML_Tests/Excel/Saving/SavingTests.cs
new file mode 100644
index 0000000..22aa34a
--- /dev/null
+++ b/ClosedXML_Tests/Excel/Saving/SavingTests.cs
@@ -0,0 +1,30 @@
+using ClosedXML.Excel;
+using NUnit.Framework;
+using System.IO;
+
+namespace ClosedXML_Tests.Excel.Saving
+{
+    [TestFixture]
+    public class SavingTests
+    {
+        [Test]
+        public void CanSuccessfullySaveFileMultipleTimes()
+        {
+            using (var wb = new XLWorkbook())
+            {
+                var sheet = wb.Worksheets.Add("TestSheet");
+                var memoryStream = new MemoryStream();
+                wb.SaveAs(memoryStream, true);
+
+                for (int i = 1; i <= 3; i++)
+                {
+                    sheet.Cell(i, 1).Value = "test" + i;
+                    wb.SaveAs(memoryStream, true);
+                }
+
+                memoryStream.Close();
+                memoryStream.Dispose();
+            }
+        }
+    }
+}