Just like in English, this section of grammar in German has hardly experienced any substantial additions or expansion for a long time now as the principle to haveprinciples that brought about these irregular verbs waswere only actively applied for creating new words in the very early days of the Germanic languages. There is the, somewhat funny, Gesellschaft zur Stärkung der Verben Gesellschaft zur Stärkung der Verben (Society for the Irregularisation of Verbs) trying to account for the lack of development here (as was already mentioned in the question's comments).
Similarly to sneak/sneaked vs. sneak/snuck, the only comparative German counterpart I can think of right now is winken/winkte/gewinkt vs. winken/(wunk)/gewunken (to be waving one's handswave) which, if not already, is most likely to enter eventually into generally accepted usage therefore coexistence(if it hasn’t already) to coexist with its olderthe regular version.
Apart from this more or less unique new creation and addition, at times you could hear mix-ups of largely homophonic verbs because ignorance of lacking knowledge or consciousness about possible differences:
- hängen/hing/gehangen vs. hängen/hängte/gehängt: Former is the intransitive version of hängen, the latter is the transitive one. So, they differ in that you would either have something/be hanging (hing) or make something hanging (hängte).
hängen/hing/gehangen vs. hängen/hängte/gehängt: The former is the intransitive version of hängen; the latter is the transitive one. So, they differ in that you would either have something/be hanging (hing) or make something hanging (hängte).
- leiden/litt/gelitten vs. leiten/leitete/geleitet: Ever so often, mathematicians are not aware of how their (linguistic) derivations might not be as logically produced as they think. I would say this is just a spleen with various individuals coming from mathematical professions because they likeliest have never considered the possibility of a lapse of memory here.
leiden/litt/gelitten vs. leiten/leitete/geleitet: Ever so often, mathematicians ignore the origin of the word ableiten (to differentiate) and say things like abgelitten. I would say this is just a spleen with various individuals coming from mathematical professions because they likely have never considered the possibility of a lapse of memory here.
- genießen/genoss/genossen vs. niesen/nieste/geniest: By the spur of the moment, at times people say (jokingly) someone/themselves might have enjoyed to have sneezed.
genießen/genoss/genossen vs. niesen/nieste/geniest: By the spur of the moment, at times people say (jokingly) genossen (enjoyed) instead of geniest (sneezed).
- schleifen/schliff/geschliffen vs. schleifen/schleifte/geschleift: For completion's purposes of this section, this pair, as a potential cause for having them mixed up, wouldn't really be that providing with a contemporary case of an occasion. They mean to hone (e.g. a piece of metal) vs. to demolish (a large structure, e.g. a castle)
schleifen/schliff/geschliffen vs. schleifen/schleifte/geschleift: Sometimes people mix up the former (meaning to hone, e.g. a piece of metal) with the latter (meaning to slight, e.g., a fortress).
It is also quite often the case that the past participle in German would beis produced erroneously, but at the same time also that not ashere the main point to look at is the actual intention to become fulfilled or achieved throughof using one version or the other, i.e. by state or progression of the action implied by the verb.
Although being lexicalised with only one, many regular verbs are occasionally producedused with twoa different past participlesparticiple in German. For example, abgeschaltet vs. abgeschalten (to switch off [e.g. the television]) stems from the regular root verb schalten which is conjugated with either of the two auxiliarauxiliary verbs in German (sein//haben). It should be phrasedconjugated accordingly in the German verbal tense of Perfekt as [Der Fernseher] ist abgeschaltet or [Der Fernseher] hat abgeschaltet (as above), but not as [Der Fernseher] ist abgeschalten or [Der Fernseher] hat abgeschalten.follows:
Der Fernseher ist abgeschaltet.*
Der Fernseher hat abgeschaltet.*
ThisThere is a tendency to also use, like it would be here then, [Der Fernseher] ist abgeschalten:
Der Fernseher ist abgeschalten.*
This stems in all likelihood from the non-obvious difference in usage of the auxiliar verbs with irregular verbs.: (ist gesprungen / hat gestanden / hat gesprochen / hat geschwiegen / ist geschritten / ist gelaufen.)