False positive with CB digital?

Ok ladies can you or is it possible to get a false positive on a CB digital (weeks estimator kind)??? I took a walmart cheapie, vvvvfl showing. Took first response vvvvfl also showing. Took one CB digital said not pregnant, but keep in mind my urine was probably diluted as I had a Starbucks Coffee on the way to get those test and finish when I was about home then took them. I had went pee once or twice after taking them, then needed to go again so I took one and it said pregnant 1-2. For it to show on the CB my first response should have been darker right?