Motl has mentioned/reviewed a recent interview with John Schwarz for the oral histories collection
https://www.aip.org/history-programs/niels-bohr-library/oral-histories/45439
and his reminiscence of earlier theories is short:
So we called the theory the dual pion model. But anyway, that’s just a historical thing which is very forgettable, because the modern interpretation is entirely different.
The general topic is mentioned as dual resonance theory. So I have taken some time to review inspire-hep looking for the alternative names that are the topic of this thread, just as a refresher
1969 K. Bardakci(UC, Berkeley), M.B. Halpern(UC, Berkeley)
Possible born term for the hadron bootstrap
1969 M.B. Halpern(UC, Berkeley), J.A. Shapiro(UC, Berkeley), S.A. Klein(Claremont Coll.)
Spin and internal symmetry in dual feynman theory
1970 K. Bardakci(UC, Berkeley), M.B. Halpern(UC, Berkeley)
New dual quark models (this is the string bit theory, is it? or is it more?) (topcited > 300)
1971 J.H. Schwarz(Princeton U.)
Dual quark-gluon model of hadrons "Our proposal is to interpret the Ramond fermions as quarks and the "Dual-pion model" bosons as gluons"
1971 M.B. Halpern(UC, Berkeley), Charles B. Thorn(UC, Berkeley)
Two faces of a dual pion - quark model. 2. Fermions and other things
1971 A. Neveu(Princeton U.), J.H. Schwarz(Princeton U.)
Quark Model of Dual Pions (topcite > 500) Interacting pseudoscalar pions are incorporated into Ramond's model of free dual fermions. By considering the emission of N−1 pions and factorizing in the quark-antiquark channel, we recover the same N-pion amplitudes as were proposed in a previous paper.
1971 Stephen Dean Ellis(Caltech)
A Dual Quark Model with Spin
1971 I. Bars(Yale U.)
Degeneracy breaking in a ghost-free dual model with spin and su(3)
1972 P.G.O. Freund(Imperial Coll., London and Chicago U., EFI) Quark spin in a dual-resonance model The foundations are laid for a dual-resonance model with a spectrum characteristic ofU6×U6×O3 symmetry. The model provides an automatic mechanism for the breaking of the collinearU6×O2 symmetry. The states on the leading Regge trajectory with the exception of the lowest (« ground ») state are all parity doubled. It is argued that there may exist « mesonic » strings with a quark at one end and anSU3-singlet spin-zero boson at the other end. These complex hadrons would have all the quantum numbers (half-integer spin, nonvanishing triality, etc.) of quarks, while not being really quarks (e.g., a baryon would not be built of three of them).
1972 Edward Corrigan(Cambridge U., DAMTP and CERN), David I. Olive(Cambridge U., DAMTP and CERN)
Fermion meson vertices in dual theories
1972 S.D. Ellis(Fermilab)
Regge pole model of pion nucleon scattering with explicit quarks
1973 K. Bardakci(UC, Berkeley), M.B. Halpern(UC, Berkeley) DUAL M - MODELS


1973 John H. Schwarz(Caltech)
Dual resonance theory ...A modification of the Veneziano model incorporating SU( N ) symmetry in a dynamical fashion is shown to have critical dimension 26− N[/size]
1973 L. Brink(Durham U. and Goteborg, ITP), D.B. Fairlie(Durham U.)
Pomeron singularities in the Fermion meson dual model
1974 J.H. Schwarz(Caltech)
Dual quark-gluon theory with dynamical color A modification of a previously proposed dual resonance theory of quarks and gluons is presented. It consists of incorporating new oscillator modes carrying color indices. The specific properties of these operators and the way they are included into the theory are completely determined by various consistency requirements. This modification of the theory has two important consequences. First, quark statistics are properly taken into account. Second, the critical dimension of space-time is reduced to d = 10−2 N , where N is the number of colors. Thus, the physically preferred choices N = 3 and d = 4 are compatible.
1974 L. Brink(Goteborg, ITP), Holger Bech Nielsen(Bohr Inst.)
Two Mass Relations for Mesons from String - Quark Duality
1975 Joel Scherk(Caltech), John H. Schwarz(Caltech)
Dual Field Theory of Quarks and Gluons " The 10-dimensional space-time of the spinor dual model is interpreted as the product of ordinary 4-dimensional space-time and a 6-dimensional compact domain, whose size is so small that it is as yet unobserved. This leads to an SU(4) symmetry group with quarks in both a 4 and a 4 multiplet. " (topcited > 200 )
1976 M. Ademollo(Florence U. and INFN, Florence), L. Brink(Goteborg, ITP), et al,
Dual String Models with Nonabelian Color and Flavor Symmetries
It seems that dual quark in the early seventies referred to the idea of adding flavour-spin SU(12) or u(6) or similar beasts in order to produce all the mesons. So it stands to reason that Schwarz considers this denomination a different way from pure string theory. He does not see any relationship with SO(32) strings or the like. So his 1971 paper prefers to use the title "quark model of dual pions" to stress the diference with group theoretical flavour games.
1972 is the year of the basic QCD paper
https://arxiv.org/abs/hep-ph/0208010
Current Algebra: Quarks and What Else? Harald Fritzsch, Murray Gell-Mann
and then SU(3) colour was still denominated quark-gluon theory, it seems.
In 1975 paper, the approach does not include pions anymore, it is "gluons", and the conclusions explain that "
The approach of this paper departs from the conventional philosophy of trying to use dual models to construct a ·more or less realistic approximstion to the hadron S matrix. Instead, we are suggesting the use of the spinor dual model as an alternative kind of quark-gluon field theory in which the input fields have color and presumably do not correspond to physical particles."