Hello tab dev,
Please remember to add the version number for your attached .twbx file when posting to the community. Thank you so much for providing the sample data. This is version 9.3 for anyone else that may open to assist.
I have attached one method of providing the answer to this question. Note that you will need to have all the months/years in the view that are being compared to do this. In the "Final" view, I have 'hidden' the first year of data since all of the potential values will always be False.
The view utilizes two different sets of table calculation to determine the comparisons. The first is the lookup(sum([sales]),-12) which uses "Table Across" to look backwards 12 months for the Sales value.
The second table calculation use "Table Down" to sum together the '1' values for 'true' conditions for Binders and Chairs. If both are summed to be equal to 2 then a True condition appears.
Sheet 4 shows the final view based on the request. Note that I have also hidden the values for 2011 (right click on 2012 header and click - 'show hidden data' if you want this to appear).
I hope this helps.