It does not necessarily show that both Goku and Vegeta were born in the same year in the new movie. It is mever shown that Goku and Vegeta are both in saiyan incnbators at the same time so they are not the same age. Even if they are in incubators at the same time one may be in for a longer period in comparison to the other. When Goku was in an incubator it was shown that Vegeta was on another planet with Nappa as their home planet got destroyed. While Vegeta was on anothet planet it was shown that Goku was still in an incubator and then Bardock decied to put him in a pod and send him to Earth where he may lived safely.
Also, Vegeta was said to be born in the Year 732 while Goku in 737 so Vegeta is 5 years older than Goku.
However, the time both have spent in the Hyperbolic time chamber make them a year older than they actually should have been and if you want to classify it as this then you can. Their physical bodies are older than their actual ages.