In　this　work,　merged　and　alternating　droplets　generated　in　a　microfluidic　double　T-junction　are　investigated　using　experiments　and　numerical　simulations.　The　double　T-junction　is　constructed　by　symmetrically　inserting　two　capillaries　into　a　microfluidic　chip　at　specific　positions.　We　explore　the　effects　of　the　two-phase　flow　rate　fraction,　capillary　tip　distance　(30　mu　m,　60　mu　m,　and　200　mu　m),　and　fluid　properties　on　droplet　formation　phenomena.　Detailed　observations　reveal　four　distinct　regimes　during　the　dynamic　evolution　of　the　two-phase　interface　morphology:　merged　state,　stable　alternating　droplets,　droplet　pairs,　and　jetting.　Two　phase　diagrams　are　obtained　to　demonstrate　that　interfacial　tension　and　dispersed　phase　viscosity　significantly　influence　these　regimes.　Moreover,　we　find　that　as　the　flow　rate　fraction　increases　from　0.054　to　0.286,　the　length　of　generated　droplets　increases　from　156　to　789　mu　m;　we　provide　a　theoretical　prediction　formula　for　dimensionless　droplet　length　accordingly.　Additionally,　our　simulations　show　fluctuating　pressure　in　dispersed　flows　throughout　the　process　of　droplet　generation.　The　simulated　pressure　in　the　dispersed　flows　fluctuates　during　the　droplet　generation　process.　The　understanding　of　the　underlying　physics　of　the　capillary-based　double　T-junction　contributes　valuable　insights　for　various　related　applications.