If the cell sizes are the same, try this in Raster Calculator:
Con(("flood01" + "flood02") == 2, 1)
The output raster attribute table will have one row and its Count field will have the number of cells.
In case the cell sizes are different you could do this with area, using Raster Calculator:
ZonalGeometry(Con(("flood01" + "flood02") == 2, 1), "VALUE", "AREA")
All overlapping cells will have the value of the total area overlapped.