SpeI (M31992) and AvrII (BBa_B0048) restriction sites have a compatible overhang (CTAG).
The SpeI-AvrII mixed site is ACTAGG. When SpeI comes from RFC10 BioBrick Suffix, the DNA scar left after a ligation is TACTAGG (see http://partsregistry.org/Help:BioBrick_Prefix_and_Suffix for details).