Sure; this is exactly what what http://photozone.de does in lens reviews. The sample images aren't always exactly the same but show similar subjects, but the technical analysis is all done for each lens on the same camera (for each brand).

For example, the sample images for Pentax's 70mm DA Limited and earlier 77mm FA Limited show statues in the same garden from roughly the same viewpoint, but they're taken in different days and without mechanical precision. However, the technical analysis, done on an optical bench and shown on the previous pages are done in a controlled environment.

If you want super-identical images, reality limits that to still-life studio setups; other Lens review sites like SLR Gear will have those; see for example the the Pentax 40mm DA Limited and 43mm FA Limited. You can see both a studio still-life and a test target. These images, by their nature, are pretty dull and can't really tell you the whole story of the lens.

The Digital Picture site linked to in other answers also shows test target images, without even a studio still-life. You may find DPReview's Lens Comparator Widget similarly helpful; it gives a colorful presentation of results and you can hover over parts of the image for actual crops from the test target. But really, I can't see much advantage of staring at test targets yourself over looking at the crunched data and reading what the reviewers are saying.

As I re-read your question, though, I think that what you're actually asking may be best covered by What characteristics make a good lens good?, which goes into what exactly the practical, visible differences are between higher-quality lenses and what you might want to look for in any samples. Once you know what you're looking for, it's not really important for the test images to be exactly identical.