Cats may synchronize their movements because they are looking for companionship and warmth. Interactions between animals can sometimes bring warmth and security, especially to social animals like cats. Synchronized movements may also be intended to indicate friendship or intimacy. Additionally, your cat may be observing your actions and learning new things by imitating them. Synchronous actions may also serve other purposes. For example, when cats feel threatened, they may synchronize their movements to increase their power and sense of threat. Another possibility is that cats synchronize their movements because they are adjusting to their biological rhythms, such as their sleep-wake cycles.
In general, there may be many reasons for cats to synchronize their movements. Sometimes they may be looking for companionship and warmth. Sometimes it may be to express friendship or intimacy, or it may be to learn new things or increase one's sense of power and threat, or even to adjust biological rhythms.