I got two oz. from one plant and only 17 grams from another grwon under the same conditions and the same strain. The 17 grams are airy and the other was rock hard. What happened?
It's necessary to have a lot more information than this to give any information for you. Did you have both plants in one pot, what kind of lighting system did you have? What strain, from what breeder? There are a million things that can make a difference in weight.
Also, when an experienced grower is looking to have an even growing crop, you have to start your seeds, veg them out, take several cuttings from each of them, and plant those rooted clones, keeping them going as future mothers for the next crop. Once you have finished the first one, you kill the mother plants from the crappy plants, and keep the good mothers, take clones from them, and now every clone you grow will grow exactly like the mother you took it from.
Thats just how it works. Everyone new to growing thinks they're just going to order some seeds, and bamo.....I'm gonna get a rockin' garden of all awsome plants. Thats not how it is....learn from each grow, and you'll earn your improved crop downt the road.
Happy growing!