I hope you can help with this problem, I am using Excel for Office 365.

I have a list of ~1,000 alphanumeric codes along with descriptions which should be the same for each of the core 5 digit part of the Code.  So 40008 and 40008C should both have the same description, the 5 digit code is the master and any alpha suffix Codes should have the same description.  In the Match column I need a formula that looks at the helper column Base (which I added for just the first 5 digits of the Code) and, where they are the same, check if the Descriptions are also the same (case insensitive), marking all the rows for that Base code.  I have used TRUE and FALSE but it could be anything as I am just using it to filter a pivot table.  If there is only one item for the base then it will be TRUE since there is nothing to compare it with.  Where there are >2 Codes for the base e.g. 40008, then even though one is the same as the Code master they are all marked as FALSE because one of them is.  A sample looks like this, Excel file attached.

Code      Description     Base       Match
40007    Desks             40007     TRUE
40008    Chair              40008     FALSE
40008C  Chair w arms   40008     FALSE
40008D  Chair              40008     FALSE
40015    Lamp              40015     TRUE
40015D  LAMP              40015     TRUE

Thanks in advance!