A certain focal-length given a fixed sensor-size is expected to show the same field of view. That is, on the same camera, two lenses of the same focal-length will give the same field-of-view. There are two catches however:

• Focal-lengths are often rounded to conventional numbers. For example, a 35mm lens may be in fact a 34mm or 36mm, or even fractional. With very wide lenses where it makes a difference, it is sometimes quoted in 0.5mm increment since a 10.5mm lens show a noticeably different field-of-view than a 10mm one but you would be hard-pressed to tell the difference between a 300.5mm and 300mm lens.
• The field-of-view frequently varies by focus-distance. You may see a certain field-of-view with the 50mm lens at infinity and a different angle when the lens is focused at 2m, for example. When a manufacturer quotes the field-of-view, it is usually with the lens focused at infinity, unless it is not capable of focusing that far, as can happen with some specialty lenses. How field-of-view varies relative to the focus-distance depends on the lens construction, so not all 35mm lenses change their field-of-view the same way when focused.