  We analyze a unique event with an M1.8 confined circular-ribbon flare on 2016
February 13, with successive formations of two circular ribbons at the same
location. The flare had two distinct phases of UV and EUV emissions with an
interval of about 270 s, of which the second peak was energetically more
important. The first episode was accompanied by the eruption of a mini-filament
and the fast elongation motion of a thin circular ribbon (CR1) along the
counterclockwise direction at a speed of about 220 km/s. Two elongated
spine-related ribbons were also observed, with the inner ribbon co-temporal
with CR1 and the remote brightenings forming ~20 s later. In the second
episode, another mini-filament erupted and formed a blowout jet. The second
circular ribbon and two spine-related ribbons showed similar elongation motions
with that during the first episode. The extrapolated 3D coronal magnetic fields
reveal the existence of a fan-spine topology, together with a quasi-separatrix
layer (QSL) halo surrounding the fan plane and another QSL structure outlining
the inner spine. We suggest that continuous null-point reconnection between the
filament and ambient open field occurs in each episode, leading to the
sequential opening of the filament and significant shifts of the fan plane
footprint. For the first time, we propose a compound eruption model of
circular-ribbon flares consisting of two sets of successively formed ribbons
and eruptions of multiple filaments in a fan-spine-type magnetic configuration.
