  We use fundamental plane (FP) distance estimates to the components of the
double cluster A2626 (cz~17,500 km/s) to constrain cluster kinematics and
estimate total binding mass. The FP coefficients for a sample of 24 early type
and S0 cluster members (alpha=1.30+/-0.36 and beta=0.31+/-0.06) are consistent
with others reported in the literature. We examine the Mg_b distributions
within both subclusters and find them to be indistinguishable. Lacking evidence
for stellar population differences, we interpret the FP zeropoint offset
(\log(D_B/D_A)=-0.037+/-0.046, where D_{cl} is distance to subcluster cl) as a
measure of the distance difference. This measurement is consistent with the
subclusters being at the same distance, and it rules out the Hubble flow
hypothesis (distances proportional to velocity) with 99% confidence; analysis
of the subcluster galaxy magnitude distributions rules out Hubble flow at 93%
confidence. Both results favor a kinematic model where the subclusters are
bound and infalling. We estimate the total cluster binding mass by modelling
the subcluster merger as radial infall. The minimum possible total binding mass
is 1.65 times higher than the sum of the standard virial masses, a difference
statistically significant at the ~3sigma level. We discuss explanations for the
inconsistency including (1) biases in the standard virial mass estimator, (2)
biases in our radial infall mass estimate, and (3) mass beyond the virialized
cluster region; if the standard virial mass is significantly in error, the
cluster has an unusually high mass to light ratio (~1000h). Because
observational signatures of departures from radial infall are absent, we
explore the implications of mass beyond the virialized, core regions.
(abridged)
