Good catch! Venovať (without sa) is an even better example because it is commonly used with both aspects. (Venovať sa is most often used intrasitively, for an ongoing or regular activity.)
And the second one is a gold mine, because many "-držať" verbs will have the same pattern, e.g. pridržať - pridŕžať, pridržiavať, pridržovať; zadržať - zadŕžať, zadržiavať, zadržovať. Interestingly, the relative frequencies of the three forms will differ for different verbs and not all verbs have all three.
And the second one is a gold mine, because many "-držať" verbs will have the same pattern, e.g. pridržať - pridŕžať, pridržiavať, pridržovať; zadržať - zadŕžať, zadržiavať, zadržovať. Interestingly, the relative frequencies of the three forms will differ for different verbs and not all verbs have all three.