Possible mixing of a diquark-antidiquark with a $p\overline{p}$ hadronic molecule

We discuss the possibility that the two nearby resonances observed by BESIII partially below the $p\overline{p}$ threshold might be due to mixing between two metastable states with the same $J^{PC}=0^{-+}$ quantum numbers, but rather different internal structure. One is a $p\overline{p}$ hadronic molecule and the other a bound state of a light-quark diquark and an antidiquark, both with spin 1 and isospin 0, a composite color antitriplet and triplet, respectively. The doubling of resonances, one of which may be interpreted as a hadronic molecule, while the other arises from $q\overline{q}$ annihilation in a state with vacuum quantum numbers, may be a more general feature than the specific case considered here.