Question: I am new to material design and still learning. 

Is it a good idea to have the primary color and the accent from similar palettes, e.g Blue 500 and Light Blue A200? Or is the whole idea of the primary/accent to create enough contrast and you should be using colors that are really different?

Answer: 
I am not sure about the material rules behind accent colours but as a digital designer I prefer to subscribe to a mix of brand, aesthetics and colour theory.

I start with the clients brand colours and work out how they appear on screen. Look at contrasts and complimentaries. Each have their place in the usability. I create a colour page for the clients to talk them through how the brand colours work and always link this back to UX. If they are lacking in a colour for particular puprsoses e.g. a contrasting colour, then I talk them into adding another colour to their brand palette.

The next step is to take into consideration users physical eyesight.
If you are following accessibility guidelines then I wouldn't be using blue on blue. It doesn't have a high enough contrast for protanopia and deuteranopia colour blindness.

And for accessibility guidelines, these are issued by Governments. And published online. Here's an example of the Australian guidelines <https://www.w3.org/TR/WCAG20/>
I think doing like you said you are not following the right guidelines of the material design.
It's a good habit to use a primary and a secondary color and light and dark variants for each color that often are not more than two.
You can find more accurate answer [here](https://material.io/design/material-theming/overview.html#material-theming) and [here](https://material.io/design/color/applying-color-to-ui.html#top-bottom-app-bars)