  It has been conjectured that the real parts of the zeros of a linear
combination of two or more $L$-functions are dense in the interval
$[1,\sigma^*]$, where $\sigma^*$ is the least upper bound of the real parts of
such zeros. In this paper we show that this is not true in general. Moreover,
we describe the optimal configuration of the zeros of linear combinations of
orthogonal Euler products by showing that the real parts of such zeros are
dense in subintervals of $[1,\sigma^*]$ whenever $\sigma^*>1$.
