Sub djon2012()
Dim i&, R&, a(), Arr(1 To 300, 1 To 10), k&
R = Worksheets("Лист1").Cells(Rows.Count, 3).End(xlUp).Row
With New Collection
      For i = 1 To R
          .Add i
      Next
      For i = 1 To 300
          Randomize
          R = Int((.Count * Rnd) + 1)
          With Worksheets("Лист1")
              a = .Range("C" & R, "L" & R).Value
         End With
         For k = 1 To UBound(a, 2)
              Arr(i, k) = a(1, k)
         Next
         .Remove (R)
      Next
End With
Worksheets("Лист2").Range("A1").Resize(300, 10) = Arr
Worksheets("Лист2").Activate
End Sub

Sub djon2012()
Dim i&, R&, a(), Arr(1 To 300, 1 To 11), k&, isExists, j&
R = Worksheets("Лист1").Cells(Rows.Count, 3).End(xlUp).Row
With New Collection
     For i = 1 To R
         .Add i
     Next
         Randomize
     For i = 1 To 300
         R = Int((.Count * Rnd) + 1)
         With Worksheets("Лист1")
             a = .Range("C" & R, "L" & R).Value
        End With
         
        isExists = False
        For j = 1 To i
        If Arr(j, 11) = R Then isExists = True
        Next
        If Not isExists Then
         For k = 1 To UBound(a, 2)
              Arr(i, k) = a(1, k)
         Next
         Arr(i, 11) = R
        Else
         i = i - 1
        End If
      Next
End With
Worksheets("Лист2").Range("A1").Resize(300, 10) = Arr
Worksheets("Лист2").Activate
End Sub

Sub qq()
      lr = Worksheets(1).Cells(Rows.Count, 3).End(xlUp).Row
      With CreateObject("Scripting.Dictionary")
          Do While .Count <= 300
              k = Int((lr * Rnd + 1))
              .Item(k) = Worksheets(1).Range("C" & k, "L" & k).Value         
          Loop
          Worksheets("Лист2").Range("A1").Resize(300, 10) = _
          Application.Transpose(Application.Transpose(.items))
          Worksheets("Лист2").Activate
      End With
End Sub

Sub djon2012()
Dim i&, R&, a(), Arr(1 To 300, 1 To 11), k&, n&
R = Worksheets("Лист1").Cells(Rows.Count, 3).End(xlUp).Row
With New Collection
      For i = 1 To R
          .Add i
      Next
      For i = 1 To 300
          Randomize
          R = Int((.Count * Rnd) + 1)
          n = .Item(R) ' вот эту строчку пропустил
          With Worksheets("Лист1")
              a = .Range("C" & n, "L" & n).Value
         End With
         For k = 1 To UBound(a, 2)
              Arr(i, k) = a(1, k)
         Next
         Arr(i, 11) = n
         .Remove (R)
      Next
End With
Worksheets("Лист2").Range("A1").Resize(300, 11) = Arr
Worksheets("Лист2").Activate
End Sub