As Robbie requested, here's the list of phono and player-piano duets from
booklet "Good Times With Your Gulbransen:"  The accompanying text says:

"Here is a stunt that will surprise nearly everybody -- to hear a
phonograph sing while you play an accompaniment on the Gulbransen.  The
wonder is how you 'get them together.'  It is quite simple.  The roll is
cut to synchronize perfectly with the record when both are played at the
right speed.

"Put the roll on first, play a few bars to get the key in your mind, then
start the record.  If it plays too low for the piano, speed it up.  If it
plays too high, reduce its speed.  Sometimes it is desirable to transpose
the roll a tone or two because the record plays better faster or slower.
In playing, pedal gently or you will drown the weaker phonograph tones.
And keep adjusting the tempo lever till you are in perfect time with the
records.  Try these selections:"

  Beloved, It is Morn; Sung by John Barnes Wells on
    Victor Record 31791; Imperial 9262
  Berceuse from Jocelyn; Sung by Alma Gluck on
    Victor Record 74369; QRS 500105
  Good-Bye; Sung by Caruso on
    Victor Record 88280; QRS 500088
  Home, Sweet Home; Sung by Amelita Galli-Curci on
    Victor Record 74511; QRS 500097
  I Hear You Calling Me; sung by John Mccormack on
    Victor Record 51724; Imperial 927
  Irish Love Songs; Sung by Schumann-Heink on
    Victor Record 87002 ; Imperial 933
  Little Grey Home in the West; Sung by Alma Gluck on
    Victor Record 64412; Imperial 936
  Lucia di Lammermoor; Sung by Tetrazzini, Caruso, Amato, Journet,
    Jacoby, Bada on Victor Record 96201; QRS 500094
  Perfect Day, A; Sung by Evan Williams on
    Victor Record 64306; QRS 500095
  Rigoletto Quartet; Sung by Sembrich, Severina, Scoti and Caruso on
    Victor Record 96001; QRS 50094
  Silver Threads Among the Gold; Sung by Elsie Baker on
    Victor Record 17474; Imperial 913
  The Sunshine of Your Smile; Sung by John McCormack on
    Victor Record 64622; QRS 500084
  Two Grenadiers, The; Sung by Clarence Whitehill on
    Victor Record 74556; QRS 500098

 [ In 1913 Welte (Poughkeepsie) issued a series of 34 rolls to be played
 [ along with a phonograph fitted with a pallet valve for generating a
 [ synchronizing pulse upon each revolution of the phonograph turntable.
 [ A corresponding slot in the music roll opened an extra hole in the
 [ tracker at the same time.  (Ref. the Welte book by Chas. Davis Smith,
 [ page 298.)  Most likely is was the piano airmotor which was "slaved"
 [ to the pulses from the phonograph; a surviving Welte piano with the
 [ special synchronizing unit has not been found.  -- Robbie