  A recent case study from AWS by Chong et al. proposes an effective
methodology for Bounded Model Checking in industry. In this paper, we report on
a follow up case study that explores the methodology from the perspective of
three research questions: (a) can proof artifacts be used across verification
tools; (b) are there bugs in verified code; and (c) can specifications be
improved. To study these questions, we port the verification tasks for
$\texttt{aws-c-common}$ library to SEAHORN and KLEE. We show the benefits of
using compiler semantics and cross-checking specifications with different
verification techniques, and call for standardizing proof library extensions to
increase specification reuse. The verification tasks discussed are publicly
available online.
