  We consider multiple orthogonal polynomials with respect to two modified
Jacobi weights on touching intervals [a,0] and [0,1], with a < 0, and study a
transition that occurs at a = -1. The transition is studied in a double scaling
limit, where we let the degree n of the polynomial tend to infinity while the
parameter a tends to -1 at a rate of O(n^{-1/2}). We obtain a Mehler-Heine type
asymptotic formula for the polynomials in this regime. The method used to
analyze the problem is the steepest descent technique for Riemann-Hilbert
problems. A key point in the analysis is the construction of a new local
parametrix.
