Fortunately the ITER project does wast amount of R&D and basic engineering that solves problems common to both design. If the problems in stellators are solved and it proves to be superior to tokamak in practice there is no need to start from scratch.
There's also quite a bit of talk going on between scientists on both projects. If I remember correctly, the microwave heating design of Wendelstein 7-X also solved a few problems for ITER and in general it's more of a friendly competition.
I view it as less of a competition than as projects working on different parts of the same problem - ITER seems to be working more on the problems of managing a fusion reaction (materials, procedures, shielding, etc.), while using a better-studied containment design with lower technical risk. Meanwhile, Wendelstein is ignoring all those other challenges in order to study an alternate containment design in isolation.
