The presence of two 
signs in EE may be explained as a revision, in which the sign in bar 16, compatible with the remaining sources, was completed with hairpins in bar 15 following bar 7. However, both signs can be authentic and it cannot be excluded that they are to be interpreted as one longer diminuendo.
Compare the passage in the sources »
category imprint: Differences between sources
issues: EE revisions, Hairpins denoting continuation
notation: Articulation, Accents, Hairpins