  It is known that a 4d N = 1 SCFT lives on D3-branes probing a local del Pezzo
Calabi-Yau singularity. The Seiberg (or toric) duality of this SCFT arises from
the Picard-Lefshetz transformation of the affine E_N 7-brane background that is
associated with the Calabi-Yau threefold. In this paper we study the duality of
the affine E_N background itself and a 5-brane probing it. We then find that
many different Type IIB 5-brane webs describe the same SCFT in 5d. We check
this duality by comparing the Nekrasov partition functions of these 5-brane web
configurations.
