I create a bar chart then create a separate view and add a new overlay of the same data but change the offset to say a year ago, I can move the chart to hunt for similar patterns. If I hover over a bar in the overlay it displays the date and price information of the main chart not the overlay.
The ability to show the date and values of the overlayed data would be very helpful in verifying that I am looking at the same period i.e. 12 months or maybe 10 years ago. The only way to verify the offset is to keep going back to another chart and calculating the offset value and verifying the chart bar pattern.