Virtual invariant pairs:

$S: BQ^2_{1} \quad U = \pmatrix{2 & 1 \cr 2 & 1} \quad D = \pmatrix{2 & 1 \cr 2 & 1}$\hfil\break
$T: Q^2_{1} \quad U = \pmatrix{1 & 2 \cr 1 & 2} \quad D = \pmatrix{1 & 2 \cr 1 & 2}$\hfil\break

$S: Q^2_{1} \quad U = \pmatrix{1 & 2 \cr 1 & 2} \quad D = \pmatrix{1 & 2 \cr 1 & 2}$\hfil\break
$T: BQ^2_{1} \quad U = \pmatrix{2 & 1 \cr 2 & 1} \quad D = \pmatrix{2 & 1 \cr 2 & 1}$\hfil\break