Early die states of the 1826/5 Large Cent show a clear undertype of a 5 beneath the 6. In later die states, the details become mushy and the undertype begins to appear more like die crumbling at the top of the six. Another diagnostic is a small die chip separated from the inner point of the 13th star. Here again, early states are strong; later states become weak and indistinct. Newcomb 8 is the only variety that qualifies as the overdate.
Relative to the "normal" 1826 Large Cents, the 1826/5 is scarce. Red-Brown and Red examples are either super scarce or may not exist at all, as none have been certified by PCGS.