Two similar anionic dyes, resazurin and resorufin, were used for persistent spectral hole burning (PSHB) experiments at 20 K in polymer matrixes in the presence and absence of N,N,N',N'-tetramethyl-pphenylenediamine (TMPD). The effects of TMPD addition on PSHB phenomena were observed with regard to hole width, hole area (relative efficiency for hole formation), and thermal stability of the holes. The differences between the trends in PSHB of these two dyes are also discussed.