Since the process is supposed to first involve the condensation of hydrogen atoms into the so-called ultra-dense state where the atom-atom distance becomes (eventually) similar to that of muonic hydrogen, it's inevitable that some amount of regular fusion when deuterium is used will also happen. This doesn't mean that the core mechanism is different between protium and deuterium or that the process is centered around ordinary fusion; it only means that nuclear fusion may occur in the latter's case as a result of the hydrogen atoms shrinking to the picometer-scale.
Mechanisms exist (example) that would allow the ejection of energetic (MeV) protons or small fragments of ultra-dense hydrogen matter from the base ultra-dense layer before the meson-producing interaction occurs. If these energetic particles interacted with other matter, some the reactions that LENR researchers have sometimes observed throughout the years could also occur as a "side-effect".
For consistency, all time scales reported here are taken from Clayton (1968). The only reaction that is of uncertain time scale is the initial proton-proton fusion, which is too slow to measure in a laboratory. So the time scale is computed from basic theory. Hansen & Kawaler (1994) give the time scale 6,000,000,000 years, whereas Clayton gives 7,900,000,000. Bohme-Vitense (1992) gives 14,000,000,000 years, but for the lower temperature of 14,000,000 Kelvins. The one thing that is certain is that the reaction is slow.
86% of 3He goes out this way
p + p –> d + e+ + nu 7.9 x 10^9 years
p + p + e- –> d + nu 10^12 years
d + p –> 3He + g 1.4 sec
3He + 3He –> 4He + 2p 2.4 x 10^5 years
According to PP fusion theory in the core of the sun: “The time scales represent how long an average particle will survive, in our sun, before experiencing the reaction. But of course many react much more quickly, many will last far longer, and many will never react at all.”
There’s roughly 10E53 protons in the sun. So ‘many react much more quickly’ does the job just fine.
Reiterating, at 14,000,000,000C, and at the pressures inside the core of the Sun, a PP fusion event will happen on the average once in 14,000,000,000 years, but because there are so many protons in the Sun, a goodly amount of fusion reactions do occur.
At room temperature and pressure, the PP fusion rate burning a few milligrams of hydrogen an average PP fusion rate much lower than the core of the Sun is expected. From this perspective, it is easy to understand why science rejects fusion in LENR. PP Fusion just cannot happen in a Ni/H reactor.