You haven't directed us to any evidence for your assertion, so it is difficult to evaluate.
I'm not a plant physiologist, so I will argue from first principles:
photosynthesis consumes CO2 and produces O2:
6CO2 +6H2O -> C6H12O6 + 6O2
respiration consumes O2 and produces CO2:
C6H12O6 + 6O2 -> 6CO2 +6H2O
Plants do both of these things at the same time for at least part of the day. During the day, in a growing plant, photosynthesis will exceed respiration: a lot of the fixed carbon is fed into anabolic processes to produce "plant stuff"; polysaccharides, proteins, nucleic acids. This means that the plant will be a net producer of O2 and a net consumer of CO2. At night there is, of course, no photosynthesis and respiration will dominate and the plant will be a net producer of CO2 and a net consumer of O2.
At certain times of the day, twilight for example, there will be a transition between these two states, and the plant will pass through a state where there will be no net flux in either of the gases.