  In a no-signaling world, the outputs of a nonlocal box cannot be completely
predetermined, a feature that is exploited in many quantum information
protocols exploiting non-locality, such as device-independent randomness
generation and quantum key distribution. This relation between non-locality and
randomness can be formally quantified through the min-entropy, a measure of the
unpredictability of the outputs that holds conditioned on the knowledge of any
adversary that is limited only by the no-signaling principle. This quantity can
easily be computed for the noisy Popescu-Rohrlich (PR) box, the paradigmatic
example of non-locality. In this paper, we consider the min-entropy associated
to several copies of noisy PR boxes. In the case where n noisy PR-boxes are
implemented using n non-communicating pairs of devices, it is known that each
PR-box behaves as an independent biased coin: the min-entropy per PR-box is
constant with the number of copies. We show that this doesn't hold in more
general scenarios where several noisy PR-boxes are implemented from a single
pair of devices, either used sequentially n times or producing n outcome bits
in a single run. In this case, the min-entropy per PR-box is smaller than the
min-entropy of a single PR-box, and it decreases as the number of copies
increases.
