Perhaps, but measuring productivity by lines of code is a problem only if there are incentives tied to the metric: if you have a system with other incentives and have two people working in the same language, lines of code is a perfectly reasonable way to judge the productivity of a programmer.

Nope. Things can be solved any number of ways. Often a simple solution with minor changes is better than a quicky designed bandaid with 10 times the LOC

It can be a metric, but it doesn't indicate productivity by itself. It's hard to use even correlated to other metrics, but loses its value if compared out of context and without knowing the code quality

that shouldn't change day by day ?

Ofcourse noone an help you if you are trying to cheat your own system.