On the content tree, is the /en-gb/home and /de-de/home-1pages the same Tree Node, just a different language variation? Or are they two different tree nodes?
Reason why i ask is usually the -1 occurs when you copy a file in the same location, the NodeAliasPath must be unique so it adds a -# at the end of things.
If they are the same tree node, then you should be able to go to the page -> Url and add a language specific alias, or see where the -1 may be.
A screenshot of your document tree will help us get closer to a solution for you!