There are obvious similarities between the Duhemian path and Quinean path to underdetermination. Both depend on the idea of some logical distance between hypothesis and experience that leaves the latter unable uniquely to fix the former. There are also significant differences that I have tried to capture with the labels "local" and "global". In the local approach, we generate observationally equivalent sets of hypotheses by adjusting individual hypotheses in some given system. The resulting equivalent systems will differ at most locally, that is, in just the hypotheses that were altered. In the Quinean approach, however, one posits ab initiothat our total system of knowledge, including science, ordinary knowledge and even mathematics and logic, is not fixed by the experience that can only impinge on it from the periphery.
When the full weight of this difference is felt, one sees that Duhem and Quine really have very different conceptions. Duhem's approach is narrowly focussed on the confirmation of scientific hypotheses by scientists in actual scientific practice. The underdetermination Quine envisages permeates our entire conceptual system, extending to physical objects, Homer's gods, subatomic entities and the abstract entities of mathematics (1951, §6). These radically different, alternative total systems envisaged by Quine are not the sort that could be generated by multiple applications of Duhemian adjustments. Indeed Quine (1975, pp. 313-15; see also Hoefer and Rosenberg, 1994) finds such an extension implausible.
Exactly because Quine's underdetermination extends all the way through to the abstract entities of mathematics themselves, it is not clear that his version of underdetermination is properly presented as a limitation of the reach of evidence in the context of the establishment of scientific theories. Is the relation over which the underdetermination prevails the relation of confirmation of inductive inference? This relation is not usually invoked in fixing the abstract entities of mathematics. Once we fix the abstract entities of our conceptual system, might Quine's underdetermination no longer affect the determining power of evidence in a scientific theory, if ever it did? Quine's statements about underdetermination are so brief and metaphorical as to preclude answers and, in my view, even a decision as to the precise nature of his notion of underdetermination and whether it is well supported.
Intermediate positions are available. Longino (2002, pp. 126-27; 1990, pp. 40-48) argues that data has no evidential import in the absence of background assumptions. While the context invoked is not as broad as that invoked by Quine, she has in mind something grander in scope than merely the other scientific hypotheses Duhem envisaged; the background assumptions may include substantive methodological claims, such as the assumption that correlations are attributable to common causes. That evidence does not uniquely determine theory is in turned traced to the lack of unique determination of these background assumptions.