  We prove upper and lower bounds for the spectral condition number of
rectangular Vandermonde matrices with nodes on the complex unit circle. The
nodes are "off the grid", pairs of nodes nearly collide, and the studied
condition number grows linearly with the inverse separation distance. Such
growth rates are known in greater generality if all nodes collide or for groups
of colliding nodes. For pairs of nodes, we provide reasonable sharp constants
that are independent of the number of nodes as long as non-colliding nodes are
well-separated.
