Two papers with identical introduction and related work
If you treat a different aspect of the topic, it is absolutely fair to split it up in two parts. The introduction will sound quite the same, but this is also the case for most introductions in a specific research field. If you define well the objective of the paper you are presenting, you should be fine. 

Here is an example of a paper (among many) splitted in two parts that takes interest in one main topic : Part 1 and Part 2