Minimize mounts for dual copy tape pool recalls

I selected 603 on tape I56774 and recalled all these files.

To my surprise, several tapes were mounted:

[root@eosctafst0105 ~]# cta-admin sq
    type tapepool logical library    vid files queued data queued oldest age priority min age max drives cur. mounts cur. files cur. data MB/s next mounts tapes capacity files on tapes data on tapes full tapes empty tapes disabled tapes rdonly tapes writable tapes
Retrieve r_harp_2          IBM1L8 L74721           32       25.8G       6966        1     300         30           0          0         0    0           0           9.0T          19399          9.3T          0           0              0            0              1
Retrieve r_harp_2          IBM1L8 L75863            9        8.9G       6966        1     300         30           0          0         0    0           0           9.0T          16629          7.1T          0           0              0            0              1
Retrieve r_harp_2          IBM1L8 L74634           13       15.8G       6966        1     300         30           0          0         0    0           0           9.0T         116978         10.9T          1           0              0            0              0
Retrieve r_harp_2          IBM1L8 L75608            4        6.9G       6963        1     300         30           0          0         0    0           0           9.0T          34570         11.7T          1           0              0            0              0
Retrieve r_harp_1          IBM355 I56774            0           0          0        0       0          0           1          0         0    0           0          15.0T          96781         21.2T          1           0              0            0              0
Retrieve r_harp_2          IBM1L8 L75046            0           0          0        0       0          0           1          0         0    0           0           9.0T          39988         12.5T          1           0              0            0              0

While I56774 contained all the files I wanted to recall in the first place: this is how I selected these.

What happened is that these files have 2 copies on different tapes and some were queued on r_harp_2 and others on r_harp_1 and this resulted in 6x the mount of mounts.

Something should be done to minimize tape mounts or at least keep them under tighter control and deterministic.

Here recalls are sometimes on r_harp_1 and sometimes on r_harp_2?

How is the pool chosen?