This is entirely possible. It simply shows that there are different levels of VII in each of those two oils. In order to be a 30wt oil, it has to show a kinematic viscosity of between 9.3cst to 12.5cst. So technically you could have one 10w30 oil with a rating of 9.4cst at 100c, and another 0w30 oil with a rating of 12.4 at 100c. This is why it's important to look at the technical data on an oil when choosing a viscosity, just so you know if you're getting an oil at the bottom, middle or top end of that particular weight. I'm not too comfortable with the 10w30 oils out there that are lower than 10cst at 100c myself. I prefer them to be a bit higher than this.