Does this cause duplicate page content penalties?

[smartwork]

Currently:

http://www.mydomain.com/product-category-c-300.html
http://www.mydomain.com/-c-300.html

both resolve to the same page, and these

http://www.mydomain.com/product-name-p-100.html
http://www.mydomain.com/-p-100.html

both resolve to the same page.

Is there a way to prevent that, so that the second line in each example is rewritten to the first line in each example?