  The introduction of deep wide-field surveys in recent years and the adoption
of machine learning techniques have led to the discoveries of
$\mathcal{O}(10^4)$ strong gravitational lensing systems and candidates.
However, the discovery of multiply lensed transients remains a rarity. Lensed
transients and especially lensed supernovae are invaluable tools to cosmology
as they allow us to constrain cosmological parameters via lens modeling and the
measurements of their time delays. In this paper, we develop a pipeline to
perform a targeted lensed transient search. We apply this pipeline to 5807
strong lenses and candidates, identified in the literature, in the DESI Legacy
Imaging Surveys Data Release 9 (DR9) footprint. For each system, we analyze
every exposure in all observed bands (DECam $g$, $r$, and $z$). Our pipeline
finds, groups, and ranks detections that are in sufficient proximity temporally
and spatially. After the first round of inspection, for promising candidate
systems, we further examine the newly available DR10 data (with additional $i$
and $\textrm{Y}$ bands). Here we present our targeted lensed supernova search
pipeline and seven new lensed supernova candidates, including a very likely
lensed supernova $-$ probably a Type Ia $-$ in a system with an Einstein radius
of $\sim 1.5''$.
