With the adjectives/adverbs solo, mismo and igual, the diminutive form, as well as sounding more familiar, is used to intensify the quality, like saying exactamente, justamente or completamente.
-Me vas a dejar solo — You're going to leave me alone
→Me vas a dejar solito — You're going to leave me all alone/all by myself
→→Lo ha hecho él solito — He did it all by himself
-Es igual que su hermano — He's the same as his brother
→Es igualito que su hermano — He's exactly the same/the spitting image of his brother
-Déjalo ahí mismo — Leave it (right) there
→Déjalo ahí mismito — Leave it right there [More emphatic]
-Es clavado a su padre — He's the spitting image of his father
→Es clavaíto