Duplicate Entries For Single Data Points Sets

I am using old macro code in excel written several years ago. I am trying to educate myself to update and improve the macros I am using but not making much progress. This macro is used to record data from a DDE link to a Data Acquisition System. The D-AQ system sends the data points to r5c3:r5c9 typically. The macro then records the data points in those cells to the next row in sequence on a specific time interval. However, the macro is recording duplicate entries for each set of data points. Sometimes just two, but has been as many as four duplicates. I have a remove duplicates macro to run, after the fact, but preventing them from occurring in the first place is the goal. I included the application.wait method at 10 second intervals after the application .OnTime method, but it isn't preventing the duplicates.

Dim delta_time As Date
Dim Count As Integer
Dim n_rows As Integer
Dim start_row As Integer
Dim col_mov As Integer

Sub initialize_button_set()
start_row = 7
Count = 0
n_rows = Worksheets("sheet1").Cells(1, 2).Value
delta_time = Worksheets("sheet1").Cells(2, 2).Value
Application.OnTime Now + delta_time, "get_data"
Rem Worksheets("sheet1").Buttons.Add 275, 0, 72, 36
Worksheets("sheet1").Buttons.Caption = "STOP"
Worksheets("sheet1").Buttons.OnAction = "Halt"
End Sub...........................