When multiple runs are combined with `summarycombine` that have the same PSD and calibration envelope files, these files are currently duplicated--see, e.g., [the calibration files](https://ldas-jobs.ligo.caltech.edu/~aditya.vijaykumar/projects/IMRTGR/O3/summaries_test/S190408an/PhenomPv2/calibration/) for one of the O3a IMR consistency test runs. While these files are not very large, it still seems preferable to only store a single copy, if possible.