It is likely that when the Zelfs universe is expanded (creating new characters in particular), there will be a need to reuse molds. This has already occured with the current releases of Zelfs, as each character currently shares a mold with another. However, the toymakers can easily make the Zelfs distinguishable from each-other using body colours, hair, eyes and patterns - nevertheless it is not a substantial challenge telling some molds apart from others.
For the 2013 releases there is a specific pattern in which each mold is used by two Zelfs (except for the Spellinda mold, which is used by three). One of these Zelfs will be available in Large form, and is therefore the namesake for the mold. The other is not available in Large form.
Starting with 2014 releases, characters do not share molds as often, and more unique character molds are being produced with less repetition.