  We report a muon spin rotation ($\mu^{+}$SR) study of the magnetic properties
of the double perovskite compound LaSrNiReO$_{6}$. Using the unique length and
time scales of the $\mu^{+}$SR technique, we successfully clarify the magnetic
ground state of LaSrNiReO$_{6}$, which was previously deemed as a spin glass
state. Instead, our $\mu^{+}$SR results point towards a long-range dynamically
ordered ground state below $T_{\rm C}= 23$ K, for which a static limit is
foreseen at $T=0$. Furthermore, between 23 K$<T\leq$300 K, three different
magnetic phases are identified: a dense ($23$ K$<T\leq75$ K), a dilute ($75$
K$<T\leq250$ K), and a paramagnetic ($T>250$ K) state. Our results reveal how
two separate, yet intertwined magnetic lattices interact within the unique
double perovskite structure and the importance of using complementary
experimental techniques to obtain a complete understanding of the microscopic
magnetic properties of complex materials.
