"Does it contain the same yeast strain as heffe, or not?"
It's quite possibly the same strain BUT not necessarily the strain you're looking for (Weihenstephan's Hefe yeast). Bottle conditioning for one or both (or neither) of these beers may be conducted with different yeast strains than the primary (from which all of the characteristic hefe flavor comes), though I don't know for sure with Weihenstephan. Breweries tend not to be particularly open about process specifics like this. I know I've heard much talk about Hefeweizen producers only using the primary strain for bottle conditioning in their local market, and using a lager strain for distribution.
Basically, there's a pretty good chance you're not culturing a strain that will give you the typical flavors of a Bavarian-style wheat beer, but one that will give you an entirely style-inappropriate character.
You can see some discussion on the topic here and here.
You should be able to confirm whether or not you have a Hefe strain by sniffing your stir plate. If you smell clove and banana there's a chance it's useable (though unfortunately both lager and Hefe yeasts tend to be profligate sulfur-producers during exponential growth, possibly confounding this method).