We are currently using WordPress for our website and we have the Marketo plugin installed and running.
We have also embedded the marketo munchkin script that we placed in the header.
Do we need both the plugin and the munchkin script, or have we duplicated efforts?
Long story short--there's quite a few different WordPress plugins that integrate with Marketo. Some offer Munchkin tracking, some offer it optionally, and some don't at all. Which specific plugin are you using?
That plugin is fairly okay -- unless you use the "prepopulation" feature which is completely not okay and which should never be used in a professional environment (any environment in which you can afford a Marketo subscription is de facto professional).
It loads and inits Munchkin a second time but that is harmless (an extra network request to download the Munchkin bootstrapper, but the second call to init() is ignored).
The plugin is no different from just inserting the Munchkin lib + Forms 2.0 embed code, except for the terrible prepopulation option.
(Also their site is suspended for nonpayment, which is kinda not good.)