It's not the same shape. Gibson did a violin-ish shape. Höfner refined the idea, and did a scaled-down gamba shape, with the drop shoulders as they should be, very accurate in its proportions. The earliest ones were flatbacks. Calling the 500/1 a "violin bass" is very inaccurate, as the upright bass and viola da gamba are viol family, not violin.
So Gibson's design of a solid violin-like body and painted f-hole was original, but Höfner took a 400 years old hollow body design and scaled it down. With the mortise-and-tenon hide glue neck joint, and even a bass bar running the length of the top, similar to uprights. No soundpost as it's only useful for arco.
If anything, Gibson stole the 500/1 shape... When Epi did the EB1 it was Höfner-shaped. They could replicate the old EB1 shape (and should have), but they chose to do a gamba silhouette and still call it EB1.