2 Lights hovering, moving after short period

Returning from evening fishing trip on Lake of Menteith driving on A873. Two white/yellow orbs stationary above high ground between Stirling and Gargunnock, smaller & duller light descended slowly down behind ridge line never reappeared, around 60 seconds later the second began flashing, lights changing colour/flashing similar to a mirror reflecting the sun. Began moving slowly in westerly direction following ridge line before dropping behind and out of sight. Shape only visible on second object, similar to a rugby ball.