  A thoroughly studied problem in Extremal Graph Theory is to find the best
possible density condition in a host graph $G$ for guaranteeing the presence of
a particular subgraph $H$ in $G$. One such classical result, due to
Bollob\'{a}s and Thomason, and independently Koml\'{o}s and Szemer\'{e}di,
states that average degree $O(k^2)$ guarantees the existence of a
$K_k$-subdivision. We study two directions extending this result. On the one
hand, Verstra\"ete conjectured that the quadratic bound $O(k^2)$ would
guarantee already two vertex-disjoint isomorphic copies of a $K_k$-subdivision.
On the other hand, Thomassen conjectured that for each $k \in \mathbb{N}$ there
is some $d = d(k)$ such that every graph with average degree at least $d$
contains a balanced subdivision of $K_k$, that is, a copy of $K_k$ where the
edges are replaced by paths of equal length. Recently, Liu and Montgomery
confirmed Thomassen's conjecture, but the optimal bound on $d(k)$ remains open.
In this paper, we show that the quadratic bound $O(k^2)$ suffices to force a
balanced $K_k$-subdivision. This gives the optimal bound on $d(k)$ needed in
Thomassen's conjecture and implies the existence of $O(1)$ many vertex-disjoint
isomorphic $K_k$-subdivisions, confirming Verstra\"ete's conjecture in a strong
sense.
