  White dwarf (WD) stars evolve simply and predictably, making them reliable
age indicators. However, self-consistent validation of the methods for
determining WD total ages has yet to be widely performed. This work uses 1565
wide ( > 100 au) WD+WD binaries and 24 new triples containing at least two WDs
to test the accuracy and validity of WD total age determinations. For these
1589 wide double-WD binaries and triples, we derive total ages of each WD using
photometric data from all-sky surveys, in conjunction with Gaia parallaxes and
current hydrogen-atmosphere WD models. Ignoring initial-to-final-mass relations
and considering only WD cooling ages, we find that roughly 21-36% of the more
massive WDs in a system have a shorter cooling age. Since more massive WDs
should be born as more massive main-sequence stars, we attribute this
unphysical disagreement as evidence of prior mergers or the presence of an
unresolved companion, suggesting that roughly 21-36% of wide WD+WD binaries
were once triples. Among the 423 wide WD+WD pairs that pass high-fidelity cuts,
we find that 25% total age uncertainties are generally appropriate for WDs with
masses > 0.63 Msun and temperatures < 12,000 K, and provide suggested inflation
factors for age uncertainties for higher-mass WDs. Overall, WDs return reliable
stellar ages, but we detail cases where total ages are least reliable,
especially for WDs < 0.63 Msun.
